diff --git a/src/api/character.zig b/api/character.zig
similarity index 100%
rename from src/api/character.zig
rename to api/character.zig
diff --git a/src/api/combat_stats.zig b/api/combat_stats.zig
similarity index 100%
rename from src/api/combat_stats.zig
rename to api/combat_stats.zig
diff --git a/src/date_time/parse.zig b/api/date_time/parse.zig
similarity index 100%
rename from src/date_time/parse.zig
rename to api/date_time/parse.zig
diff --git a/src/date_time/timegm.c b/api/date_time/timegm.c
similarity index 100%
rename from src/date_time/timegm.c
rename to api/date_time/timegm.c
diff --git a/src/date_time/timegm.h b/api/date_time/timegm.h
similarity index 100%
rename from src/date_time/timegm.h
rename to api/date_time/timegm.h
diff --git a/src/api/enum_string_utils.zig b/api/enum_string_utils.zig
similarity index 100%
rename from src/api/enum_string_utils.zig
rename to api/enum_string_utils.zig
diff --git a/src/api/equipment.zig b/api/equipment.zig
similarity index 100%
rename from src/api/equipment.zig
rename to api/equipment.zig
diff --git a/src/api/json_utils.zig b/api/json_utils.zig
similarity index 100%
rename from src/api/json_utils.zig
rename to api/json_utils.zig
diff --git a/api/position.zig b/api/position.zig
new file mode 100644
index 0000000..c2e2f23
--- /dev/null
+++ b/api/position.zig
@@ -0,0 +1,28 @@
+const std = @import("std");
+const Position = @This();
+
+x: i64,
+y: i64,
+
+pub fn init(x: i64, y: i64) Position {
+    return Position{
+        .x = x,
+        .y = y
+    };
+}
+
+pub fn eql(self: Position, other: Position) bool {
+    return self.x == other.x and self.y == other.y;
+}
+
+pub fn format(
+    self: Position,
+    comptime fmt: []const u8,
+    options: std.fmt.FormatOptions,
+    writer: anytype,
+) !void {
+    _ = fmt;
+    _ = options;
+
+    try writer.print("{{ {}, {} }}", .{self.x, self.y});
+}
diff --git a/api/root.zig b/api/root.zig
new file mode 100644
index 0000000..06f3a7f
--- /dev/null
+++ b/api/root.zig
@@ -0,0 +1,8 @@
+
+pub const Server = @import("server.zig");
+pub const Position = @import("position.zig");
+pub const BoundedSlotsArray = @import("slot_array.zig").BoundedSlotsArray;
+
+pub const Error = Server.APIError;
+pub const ItemId = Server.ItemId;
+pub const ItemIdQuantity = Server.ItemIdQuantity;
diff --git a/src/api/server.zig b/api/server.zig
similarity index 99%
rename from src/api/server.zig
rename to api/server.zig
index ba6c0c3..fe2a717 100644
--- a/src/api/server.zig
+++ b/api/server.zig
@@ -4,7 +4,7 @@ const json = std.json;
 const Allocator = std.mem.Allocator;
 
 // TODO: Maybe it would be good to move date time parsing to separate module
-pub const parseDateTime = @import("../date_time/parse.zig").parseDateTime;
+pub const parseDateTime = @import("./date_time/parse.zig").parseDateTime;
 
 const json_utils = @import("json_utils.zig");
 pub const Character = @import("character.zig");
@@ -303,6 +303,13 @@ pub const ItemIdQuantity = struct {
     id: ItemId,
     quantity: u64,
 
+    pub fn init(id: ItemId, quantity: u64) ItemIdQuantity {
+        return ItemIdQuantity{
+            .id = id,
+            .quantity = quantity
+        };
+    }
+
     pub fn parse(api: *Server, obj: json.ObjectMap) !ItemIdQuantity {
         const code = try json_utils.getStringRequired(obj, "code");
         const quantity = try json_utils.getIntegerRequired(obj, "quantity");
@@ -1851,6 +1858,11 @@ pub fn getItem(self: *Server, code: []const u8) APIError!?Item {
     }
 }
 
+pub fn getItemById(self: *Server, id: ItemId) APIError!?Item {
+    const code = self.getItemCode(id) orelse return null;
+    return self.getItem(code);
+}
+
 pub const ItemOptions = struct {
     craft_material: ?[]const u8 = null,
     craft_skill: ?Skill = null,
diff --git a/src/api/skill_stats.zig b/api/skill_stats.zig
similarity index 100%
rename from src/api/skill_stats.zig
rename to api/skill_stats.zig
diff --git a/src/api/slot.zig b/api/slot.zig
similarity index 100%
rename from src/api/slot.zig
rename to api/slot.zig
diff --git a/src/api/slot_array.zig b/api/slot_array.zig
similarity index 100%
rename from src/api/slot_array.zig
rename to api/slot_array.zig
diff --git a/build.zig b/build.zig
index 015b346..ceaa814 100644
--- a/build.zig
+++ b/build.zig
@@ -1,41 +1,91 @@
 const std = @import("std");
+const ResolvedTarget = std.Build.ResolvedTarget;
+const OptimizeMode = std.Build.OptimizeMode;
+const Module = std.Build.Module;
 
 pub fn build(b: *std.Build) void {
     const target = b.standardTargetOptions(.{});
     const optimize = b.standardOptimizeOption(.{});
 
-    const exe = b.addExecutable(.{
-        .name = "artificer",
-        .root_source_file = b.path("src/main.zig"),
-        .target = target,
-        .optimize = optimize,
-    });
-    exe.linkLibC();
-    exe.addIncludePath(b.path("src/date_time"));
-    exe.addCSourceFile(.{ .file = b.path("src/date_time/timegm.c") });
-
-    b.installArtifact(exe);
-
-    const run_cmd = b.addRunArtifact(exe);
-    run_cmd.step.dependOn(b.getInstallStep());
-
-    if (b.args) |args| {
-        run_cmd.addArgs(args);
+    var api: *Module = undefined;
+    {
+        api = b.createModule(.{
+            .root_source_file = b.path("api/root.zig"),
+            .target = target,
+            .optimize = optimize,
+            .link_libc = true,
+        });
+        api.addIncludePath(b.path("api/date_time"));
+        api.addCSourceFile(.{ .file = b.path("api/date_time/timegm.c") });
     }
 
-    const run_step = b.step("run", "Run the app");
-    run_step.dependOn(&run_cmd.step);
+    var lib: *Module = undefined;
+    {
+        lib = b.createModule(.{
+            .root_source_file = b.path("lib/root.zig"),
+            .target = target,
+            .optimize = optimize,
+        });
+        lib.addImport("artifacts-api", api);
 
-    const exe_unit_tests = b.addTest(.{
-        .root_source_file = b.path("src/artifacts.zig"),
-        .target = target,
-        .optimize = optimize,
-    });
-    exe_unit_tests.linkLibC();
-    exe_unit_tests.addIncludePath(b.path("src"));
-    exe_unit_tests.addCSourceFile(.{ .file = b.path("src/timegm.c") });
+        const unit_tests = b.addTest(.{
+            .root_source_file = b.path("lib/root.zig"),
+            .target = target,
+            .optimize = optimize,
+        });
 
-    const run_exe_unit_tests = b.addRunArtifact(exe_unit_tests);
-    const test_step = b.step("test", "Run unit tests");
-    test_step.dependOn(&run_exe_unit_tests.step);
+        const run_unit_tests = b.addRunArtifact(unit_tests);
+        const test_step = b.step("test-lib", "Run lib unit tests");
+        test_step.dependOn(&run_unit_tests.step);
+    }
+
+    {
+        const cli = b.addExecutable(.{
+            .name = "artificer",
+            .root_source_file = b.path("cli/main.zig"),
+            .target = target,
+            .optimize = optimize,
+        });
+        cli.root_module.addImport("artificer", lib);
+        b.installArtifact(cli);
+
+        const run_cmd = b.addRunArtifact(cli);
+        run_cmd.step.dependOn(b.getInstallStep());
+
+        if (b.args) |args| {
+            run_cmd.addArgs(args);
+        }
+
+        const run_step = b.step("run-cli", "Run the CLI");
+        run_step.dependOn(&run_cmd.step);
+    }
+
+    {
+        const raylib_dep = b.dependency("raylib-zig", .{
+            .target = target,
+            .optimize = optimize,
+        });
+
+        const gui = b.addExecutable(.{
+            .name = "artificer-gui",
+            .root_source_file = b.path("gui/main.zig"),
+            .target = target,
+            .optimize = optimize,
+        });
+        gui.root_module.addImport("artificer", lib);
+        gui.linkLibrary(raylib_dep.artifact("raylib"));
+        gui.root_module.addImport("raylib", raylib_dep.module("raylib"));
+
+        b.installArtifact(gui);
+
+        const run_cmd = b.addRunArtifact(gui);
+        run_cmd.step.dependOn(b.getInstallStep());
+
+        if (b.args) |args| {
+            run_cmd.addArgs(args);
+        }
+
+        const run_step = b.step("run-gui", "Run the GUI");
+        run_step.dependOn(&run_cmd.step);
+    }
 }
diff --git a/build.zig.zon b/build.zig.zon
index dadd4eb..4338e9e 100644
--- a/build.zig.zon
+++ b/build.zig.zon
@@ -2,6 +2,11 @@
     .name = "artificer",
     .version = "0.1.0",
     .minimum_zig_version = "0.12.0",
-    .dependencies = .{ },
+    .dependencies = .{
+	 .@"raylib-zig" = .{
+	    .url = "https://github.com/Not-Nik/raylib-zig/archive/43d15b05c2b97cab30103fa2b46cff26e91619ec.tar.gz",
+	    .hash = "12204a223b19043e17b79300413d02f60fc8004c0d9629b8d8072831e352a78bf212"
+	},
+    },
     .paths = .{ "" },
 }
diff --git a/cli/main.zig b/cli/main.zig
new file mode 100644
index 0000000..160a077
--- /dev/null
+++ b/cli/main.zig
@@ -0,0 +1,42 @@
+const std = @import("std");
+const Artificer = @import("artificer");
+const Allocator = std.mem.Allocator;
+
+fn getAPITokenFromArgs(allocator: Allocator) !?[]u8 {
+    const args = try std.process.argsAlloc(allocator);
+    defer std.process.argsFree(allocator, args);
+
+    if (args.len < 2) {
+        return null;
+    }
+
+    const filename = args[1];
+    const cwd = std.fs.cwd();
+    var token_buffer: [256]u8 = undefined;
+    const token = try cwd.readFile(filename, &token_buffer);
+
+    return try allocator.dupe(u8, std.mem.trim(u8,token,"\n\t "));
+}
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    defer _ = gpa.deinit();
+    const allocator = gpa.allocator();
+
+    const token = (try getAPITokenFromArgs(allocator)) orelse return error.MissingToken;
+    defer allocator.free(token);
+
+    var artificer = try Artificer.init(allocator, token);
+    defer artificer.deinit();
+
+    std.log.info("Starting main loop", .{});
+    while (true) {
+        const waitUntil = artificer.nextStepAt();
+        const duration = waitUntil - std.time.timestamp();
+        if (duration > 0) {
+            std.time.sleep(@intCast(duration));
+        }
+
+        try artificer.step();
+    }
+}
diff --git a/gui/main.zig b/gui/main.zig
new file mode 100644
index 0000000..4ae120f
--- /dev/null
+++ b/gui/main.zig
@@ -0,0 +1,18 @@
+const rl = @import("raylib");
+
+pub fn main() anyerror!void {
+    rl.initWindow(800, 450, "Artificer");
+    defer rl.closeWindow();
+
+    rl.setTargetFPS(60);
+
+    while (!rl.windowShouldClose()) {
+
+        rl.beginDrawing();
+        defer rl.endDrawing();
+
+        rl.clearBackground(rl.Color.white);
+
+        rl.drawText("Congrats! You created your first window!", 190, 200, 20, rl.Color.light_gray);
+    }
+}
diff --git a/src/character_brain.zig b/lib/brain.zig
similarity index 95%
rename from src/character_brain.zig
rename to lib/brain.zig
index 62dbe1c..af75fd2 100644
--- a/src/character_brain.zig
+++ b/lib/brain.zig
@@ -1,9 +1,12 @@
 const std = @import("std");
-const Server = @import("./api/server.zig");
+const ArtifactsAPI = @import("artifacts-api");
+const Server = ArtifactsAPI.Server;
 const Allocator = std.mem.Allocator;
 const Position = Server.Position;
 const assert = std.debug.assert;
 
+const CharacterTask = @import("./task.zig").Task;
+
 const CharacterBrain = @This();
 
 const bank_position: Position = .{ .x = 4, .y = 1 }; // TODO: Figure this out dynamically
@@ -98,38 +101,6 @@ comptime {
     assert(@typeInfo(QueuedAction).Union.fields.len == @typeInfo(QueuedActionResult).Union.fields.len);
 }
 
-pub const CharacterTask = union(enum) {
-    fight: struct {
-        at: Position,
-        target: Server.ItemIdQuantity,
-        progress: u64 = 0,
-    },
-    gather: struct {
-        at: Position,
-        target: Server.ItemIdQuantity,
-        progress: u64 = 0,
-    },
-    craft: struct {
-        at: Position,
-        target: Server.ItemIdQuantity,
-        progress: u64 = 0,
-    },
-
-    pub fn isComplete(self: CharacterTask) bool {
-        return switch (self) {
-            .fight => |args| {
-                return args.progress >= args.target.quantity;
-            },
-            .gather => |args| {
-                return args.progress >= args.target.quantity;
-            },
-            .craft => |args| {
-                return args.progress >= args.target.quantity;
-            }
-        };
-    }
-};
-
 name: []const u8,
 action_queue: std.ArrayList(QueuedAction),
 task: ?*CharacterTask = null,
@@ -397,7 +368,7 @@ fn onActionCompleted(self: *CharacterBrain, result: QueuedActionResult) void {
                 const fight_result: Server.FightResult = r;
                 const drops = fight_result.fight.drops;
 
-                args.progress += drops.getQuantity(args.target.id);
+                args.progress += drops.getQuantity(args.until.item.id);
             }
         },
         .gather => |*args| {
@@ -405,7 +376,7 @@ fn onActionCompleted(self: *CharacterBrain, result: QueuedActionResult) void {
                 const gather_resutl: Server.GatherResult = r;
                 const items = gather_resutl.details.items;
 
-                args.progress += items.getQuantity(args.target.id);
+                args.progress += items.getQuantity(args.until.item.id);
             }
         },
         .craft => |*args| {
diff --git a/lib/root.zig b/lib/root.zig
new file mode 100644
index 0000000..2500b95
--- /dev/null
+++ b/lib/root.zig
@@ -0,0 +1,134 @@
+const std = @import("std");
+const Api = @import("artifacts-api");
+const Allocator = std.mem.Allocator;
+
+const CharacterBrain = @import("./brain.zig");
+
+const Artificer = @This();
+
+const expiration_margin: u64 = 100 * std.time.ns_per_ms; // 100ms
+const server_down_retry_interval = 5; // minutes
+
+server: Api.Server,
+characters: std.ArrayList(CharacterBrain),
+
+paused_until: ?i64 = null,
+
+pub fn init(allocator: Allocator, token: []const u8) !Artificer {
+    var server = try Api.Server.init(allocator);
+    errdefer server.deinit();
+
+    try server.setToken(token);
+
+    var characters = std.ArrayList(CharacterBrain).init(allocator);
+    defer characters.deinit();
+    // TODO: Add character deinit
+
+    // const chars = try api.listMyCharacters();
+    // defer chars.deinit();
+
+    // for (chars.items) |char| {
+    //     try scheduler.addCharacter(char.name);
+    // }
+
+    return Artificer{
+        .server = server,
+        .characters = characters
+    };
+}
+
+pub fn deinit(self: Artificer) void {
+    for (self.characters.items) |brain| {
+        brain.deinit();
+    }
+    self.characters.deinit();
+}
+
+pub fn step(self: *Artificer) !void {
+    if (self.paused_until) |paused_until| {
+        if (std.time.timestamp() < paused_until) {
+            return;
+        }
+        self.paused_until = null;
+    }
+
+    runNextActions(self.characters.items, &self.server) catch |err| switch (err) {
+        Api.Error.ServerUnavailable => {
+            self.paused_until = std.time.timestamp() + std.time.ns_per_min * server_down_retry_interval;
+            std.log.warn("Server is down, retrying in {}min", .{ server_down_retry_interval });
+            return;
+        },
+        else => return err
+    };
+
+    for (self.characters.items) |*brain| {
+        if (brain.action_queue.items.len > 0) continue;
+
+        if (brain.isTaskFinished()) {
+            if (try brain.depositItemsToBank(&self.server)) {
+                continue;
+            }
+            brain.task = null;
+        }
+
+        if (brain.task == null) {
+            // var next_tasks = try task_tree.listNextTasks();
+            // defer next_tasks.deinit();
+            //
+            // if (next_tasks.items.len > 0) {
+            //     const next_task_index = random.intRangeLessThan(usize, 0, next_tasks.items.len);
+            //     brain.task = next_tasks.items[next_task_index];
+            // }
+        }
+
+        try brain.performTask(&self.server);
+    }
+}
+
+pub fn nextStepAt(self: *Artificer) i64 {
+    if (self.paused_until) |paused_until| {
+        return paused_until;
+    }
+
+    return earliestCooldown(self.characters.items, &self.server) orelse 0;
+}
+
+fn earliestCooldown(characters: []CharacterBrain, api: *Api.Server) ?i64 {
+    var earliest_cooldown: ?i64 = null;
+    for (characters) |*brain| {
+        if (brain.action_queue.items.len == 0) continue;
+
+        const character = api.findCharacter(brain.name).?;
+        const cooldown: i64 = @intFromFloat(character.cooldown_expiration * std.time.ns_per_s);
+
+        if (earliest_cooldown == null or earliest_cooldown.? > cooldown) {
+            earliest_cooldown = cooldown;
+        }
+    }
+
+    return earliest_cooldown;
+}
+
+fn runNextActions(characters: []CharacterBrain, api: *Api.Server) !void {
+    const maybe_earliest_cooldown = earliestCooldown(characters, api);
+    if (maybe_earliest_cooldown == null) return;
+
+    const earliest_cooldown = maybe_earliest_cooldown.?;
+    if (earliest_cooldown < std.time.timestamp()) return;
+
+    for (characters) |*brain| {
+        if (brain.action_queue.items.len == 0) continue;
+
+        const character = api.findCharacter(brain.name).?;
+        const cooldown: u64 = @intFromFloat(character.cooldown_expiration * std.time.ns_per_s);
+
+        if (earliest_cooldown > cooldown) {
+            try brain.performNextAction(api);
+        }
+    }
+}
+
+fn currentTime() f64 {
+    const timestamp: f64 = @floatFromInt(std.time.milliTimestamp());
+    return timestamp / std.time.ms_per_s;
+}
diff --git a/lib/task.zig b/lib/task.zig
new file mode 100644
index 0000000..33e648c
--- /dev/null
+++ b/lib/task.zig
@@ -0,0 +1,39 @@
+const Api = @import("artifacts-api");
+const Position = Api.Position;
+
+pub const UntilCondition = union(enum) {
+    xp: u64,
+    item: Api.ItemIdQuantity,
+};
+
+pub const Task = union(enum) {
+    fight: struct {
+        at: Position,
+        until: UntilCondition,
+        progress: u64 = 0,
+    },
+    gather: struct {
+        at: Position,
+        until: UntilCondition,
+        progress: u64 = 0,
+    },
+    craft: struct {
+        at: Position,
+        target: Api.ItemIdQuantity,
+        progress: u64 = 0,
+    },
+
+    pub fn isComplete(self: Task) bool {
+        return switch (self) {
+            .fight => |args| {
+                return args.progress >= args.until.item.quantity;
+            },
+            .gather => |args| {
+                return args.progress >= args.until.item.quantity;
+            },
+            .craft => |args| {
+                return args.progress >= args.target.quantity;
+            }
+        };
+    }
+};
diff --git a/lib/task_graph.zig b/lib/task_graph.zig
new file mode 100644
index 0000000..2641351
--- /dev/null
+++ b/lib/task_graph.zig
@@ -0,0 +1,234 @@
+const std = @import("std");
+const Api = @import("artifacts-api");
+const Allocator = std.mem.Allocator;
+
+const TaskGraph = @This();
+const CharacterTask = @import("./task.zig").Task;
+
+const TaskNodeId = u16;
+const TaskNode = struct {
+    const Dependencies = std.BoundedArray(TaskNodeId, 8);
+    const MissingItems = Api.BoundedSlotsArray(8);
+
+    task: CharacterTask,
+    dependencies: Dependencies = Dependencies.init(0) catch unreachable,
+    missing_items: MissingItems = MissingItems.init(),
+
+    pub fn format(
+        self: TaskNode,
+        comptime fmt: []const u8,
+        options: std.fmt.FormatOptions,
+        writer: anytype,
+    ) !void {
+        _ = options;
+        _ = fmt;
+
+        switch (self.task) {
+            .fight => |args| {
+                const item = self.api.getItemCode(args.target.id).?;
+                try writer.print("Task{{ .fight = {{ \"{s}\" x {} }}, .at = {} }}\n", .{item, args.target.quantity, args.at});
+            },
+            .gather => |args| {
+                const item = self.api.getItemCode(args.target.id).?;
+                try writer.print("Task{{ .gather = {{ \"{s}\" x {} }}, .at = {} }}\n", .{item, args.target.quantity, args.at});
+            },
+            .craft => |args| {
+                const item = self.api.getItemCode(args.target.id).?;
+                try writer.print("Task{{ .craft = {{ \"{s}\" x {} }}, .at = {} }}\n", .{item, args.target.quantity, args.at});
+            },
+        }
+
+        // var child_nodes = try self.listByParent(node_id);
+        // defer child_nodes.deinit();
+        //
+        // for (child_nodes.items) |child_node| {
+        //     try self.formatNode(child_node, level + 1, writer);
+        // }
+        // for (node.additional_items.slots.constSlice()) |slot| {
+        //     const item_code = self.api.getItemCode(slot.id).?;
+        //     try writer.writeBytesNTimes("  ", level+1);
+        //     try writer.print("+ {{ \"{s}\" x {} }}\n", .{item_code, slot.quantity});
+        // }
+    }
+};
+
+const Nodes = std.ArrayList(TaskNode);
+
+nodes: Nodes,
+
+pub fn init(allocator: Allocator) TaskGraph {
+    return TaskGraph{ .nodes = Nodes.init(allocator) };
+}
+
+pub fn deinit(self: TaskGraph) void {
+    self.nodes.deinit();
+}
+
+fn get(self: *TaskGraph, id: TaskNodeId) *TaskNode {
+    return &self.nodes.items[id];
+}
+
+fn addTask(self: *TaskGraph, node: TaskNode) !TaskNodeId {
+    try self.nodes.append(node);
+    return @intCast(self.nodes.items.len-1);
+}
+
+fn addFightTask(self: *TaskGraph, api: *Api.Server, item_id: Api.ItemId, quantity: u64) !TaskNodeId {
+    const item_code = api.getItemCode(item_id) orelse return error.ItemNotFound;
+    const monsters = try api.getMonsters(.{ .drop = item_code });
+    defer monsters.deinit();
+
+    if (monsters.items.len == 0) return error.ResourceNotFound;
+    if (monsters.items.len > 1) std.log.warn("Multiple monsters exist for target item", .{});
+    const monster_code = monsters.items[0].code;
+
+    const resource_maps = try self.api.getMaps(.{ .code = monster_code });
+    defer resource_maps.deinit();
+
+    // This monster currently doesn't exist on the map. Probably only spawns in certain situations.
+    if (resource_maps.items.len == 0) return error.MapNotFound;
+
+    if (resource_maps.items.len > 1) std.log.warn("Multiple map locations exist for monster", .{});
+    const resource_map = resource_maps.items[0];
+
+    return try self.addTask(TaskNode{
+        .task = .{
+            .fight = .{
+                .at = resource_map.position,
+                .until = .{ .item = Api.ItemIdQuantity.init(item_id, quantity) }
+            }
+        }
+    });
+}
+
+fn addGatherTask(self: *TaskGraph, api: *Api.Server, item_id: Api.ItemId, quantity: u64) !TaskNodeId {
+    const item_code = api.getItemCode(item_id) orelse return error.ItemNotFound;
+    const resources = try api.getResources(.{ .drop = item_code });
+    defer resources.deinit();
+
+    if (resources.items.len == 0) return error.ResourceNotFound;
+    if (resources.items.len > 1) std.log.warn("Multiple resources exist for target item", .{});
+    const resource_code = resources.items[0].code;
+
+    const resource_maps = try self.api.getMaps(.{ .code = resource_code });
+    defer resource_maps.deinit();
+
+    if (resource_maps.items.len == 0) return error.MapNotFound;
+    if (resource_maps.items.len > 1) std.log.warn("Multiple map locations exist for resource", .{});
+    const resource_map = resource_maps.items[0];
+
+    return try self.addTask(TaskNode{
+        .task = .{
+            .gather = .{
+                .at = resource_map.position,
+                .until = .{ .item = Api.ItemIdQuantity.init(item_id, quantity) }
+            }
+        }
+    });
+}
+
+fn addCraftTaskShallow(self: *TaskGraph, api: *Api.Server, item_id: Api.ItemId, quantity: u64) !TaskNodeId {
+    const item = (try api.getItemById(item_id)) orelse return error.ItemNotFound;
+    const recipe = item.craft orelse return error.RecipeNotFound;
+
+    const skill_str = Api.Server.SkillUtils.toString(recipe.skill);
+    const workshop_maps = try self.api.getMaps(.{ .code = skill_str, .type = .workshop });
+    defer workshop_maps.deinit();
+
+    if (workshop_maps.items.len == 0) return error.WorkshopNotFound;
+    if (workshop_maps.items.len > 1) std.log.warn("Multiple workshop locations exist", .{});
+
+    return try self.addTask(TaskNode{
+        .task = .{
+            .craft = .{
+                .at = workshop_maps.items[0].position,
+                .target = Api.ItemIdQuantity.init(item_id, quantity)
+            }
+        }
+    });
+}
+
+fn addCraftTask(self: *TaskGraph, api: *Api.Server, item_id: Api.ItemId, quantity: u64) !TaskNodeId {
+    const node_id = try self.addCraftTaskShallow(api, item_id, quantity);
+    var node = self.get(node_id);
+
+    const item = (try api.getItemById(item_id)) orelse return error.ItemNotFound;
+    const recipe = item.craft orelse return error.RecipeNotFound;
+
+    const craft_count = recipe.quantity;
+
+    for (recipe.items.slots.constSlice()) |material| {
+        const needed_quantity = material.quantity * craft_count;
+
+        if (try self.addAutoTask(api, material.id, needed_quantity)) |dependency_id| {
+            try node.dependencies.append(dependency_id);
+        } else {
+            try node.missing_items.add(material.id, needed_quantity);
+        }
+    }
+
+    return node_id;
+}
+
+// TODO: Remove `anyerror` from function declaration
+fn addAutoTask(self: *TaskGraph, api: *Api.Server, item_id: Api.ItemId, quantity: u64) anyerror!?TaskNodeId {
+    const item = (try self.api.getItemById(item_id)) orelse return error.ItemNotFound;
+
+    if (item.craft != null) {
+        return try self.addCraftTask(api, item_id, quantity);
+    } else if (item.type == .resource) {
+        const eql = std.mem.eql;
+        if (eql(u8, item.subtype, "mining") or eql(u8, item.subtype, "fishing") or eql(u8, item.subtype, "woodcutting")) {
+            return try self.addGatherTask(api, item_id, quantity);
+        } else if (eql(u8, item.subtype, "mob")) {
+            return try self.addFightTask(api, item_id, quantity);
+        }
+    }
+
+    return null;
+}
+
+fn printTask(self: *TaskGraph, api: *Api.Server, node_id: TaskNodeId) void {
+    self.printTaskLevel(api, node_id, 0);
+}
+
+fn writeIdentation(level: u32) void {
+    const mutex = std.debug.getStderrMutex();
+    mutex.lock();
+    defer mutex.unlock();
+
+    const stderr = std.io.getStdErr().writer();
+    stderr.writeBytesNTimes("  ", level) catch return;
+}
+
+fn printTaskLevel(self: *TaskGraph, api: *Api.Server, node_id: TaskNodeId, level: u32) void {
+    const node = self.get(node_id);
+    const print = std.debug.print;
+
+    writeIdentation(level);
+    switch (node.task) {
+        .fight => |args| {
+            const target_item = args.until.item;
+            const item = api.getItemCode(target_item.id).?;
+            print("Task{{ .fight = {{ \"{s}\" x {} }}, .at = {} }}\n", .{item, target_item.quantity, args.at});
+        },
+        .gather => |args| {
+            const target_item = args.until.item;
+            const item = api.getItemCode(target_item.id).?;
+            print("Task{{ .gather = {{ \"{s}\" x {} }}, .at = {} }}\n", .{item, target_item.quantity, args.at});
+        },
+        .craft => |args| {
+            const item = api.getItemCode(args.target.id).?;
+            print("Task{{ .craft = {{ \"{s}\" x {} }}, .at = {} }}\n", .{item, args.target.quantity, args.at});
+        },
+    }
+
+    for (node.dependencies.constSlice()) |dependency| {
+        self.printTaskLevel(dependency, level + 1);
+    }
+    for (node.missing_items.slots.constSlice()) |slot| {
+        const item_code = api.getItemCode(slot.id).?;
+        writeIdentation(level+1);
+        print("+ {{ \"{s}\" x {} }}\n", .{item_code, slot.quantity});
+    }
+}
diff --git a/src/api/position.zig b/src/api/position.zig
deleted file mode 100644
index f8cf052..0000000
--- a/src/api/position.zig
+++ /dev/null
@@ -1,15 +0,0 @@
-const Position = @This();
-
-x: i64,
-y: i64,
-
-pub fn init(x: i64, y: i64) Position {
-    return Position{
-        .x = x,
-        .y = y
-    };
-}
-
-pub fn eql(self: Position, other: Position) bool {
-    return self.x == other.x and self.y == other.y;
-}
diff --git a/src/main.zig b/src/main.zig
deleted file mode 100644
index f826514..0000000
--- a/src/main.zig
+++ /dev/null
@@ -1,374 +0,0 @@
-const std = @import("std");
-const Allocator = std.mem.Allocator;
-const assert = std.debug.assert;
-
-const Position = @import("./api/position.zig");
-const Server = @import("./api/server.zig");
-const CharacterBrain = @import("./character_brain.zig");
-const BoundedSlotsArray = @import("./api/slot_array.zig").BoundedSlotsArray;
-
-// pub const std_options = .{ .log_level = .debug };
-
-fn todo() void {
-    unreachable;
-}
-
-fn currentTime() f64 {
-    const timestamp: f64 = @floatFromInt(std.time.milliTimestamp());
-    return timestamp / std.time.ms_per_s;
-}
-
-const GoalManager = struct {
-    api: *Server,
-    allocator: Allocator,
-    characters: std.ArrayList(CharacterBrain),
-    expiration_margin: f64 = 0.1, // 100ms
-
-    fn init(api: *Server, allocator: Allocator) GoalManager {
-        return GoalManager{
-            .api = api,
-            .allocator = allocator,
-            .characters = std.ArrayList(CharacterBrain).init(allocator)
-        };
-    }
-
-    fn addCharacter(self: *GoalManager, name: []const u8) !void {
-        const character = try CharacterBrain.init(self.allocator, name);
-        try self.characters.append(character);
-    }
-
-    fn deinit(self: GoalManager) void {
-        for (self.characters.items) |brain| {
-            brain.deinit();
-        }
-        self.characters.deinit();
-    }
-
-    fn runNextAction(self: *GoalManager) !void {
-        var earliest_cooldown: f64 = 0;
-        var earliest_character: ?*CharacterBrain = null;
-        for (self.characters.items) |*brain| {
-            if (brain.action_queue.items.len == 0) continue;
-
-            const character = self.api.findCharacter(brain.name).?;
-            if (earliest_character == null or earliest_cooldown > character.cooldown_expiration) {
-                earliest_character = brain;
-                earliest_cooldown = character.cooldown_expiration;
-            }
-        }
-
-        if (earliest_character == null) return;
-
-        const now = currentTime();
-        if (earliest_cooldown > now) {
-            const duration_s = earliest_cooldown - now + self.expiration_margin;
-            const duration_ms: u64 = @intFromFloat(@trunc(duration_s * std.time.ms_per_s));
-            std.log.debug("waiting for {d:.3}s", .{duration_s});
-            std.time.sleep(std.time.ns_per_ms * duration_ms);
-        }
-
-        try earliest_character.?.performNextAction(self.api);
-    }
-};
-
-fn getAPITokenFromArgs(allocator: Allocator) !?[]u8 {
-    const args = try std.process.argsAlloc(allocator);
-    defer std.process.argsFree(allocator, args);
-
-    if (args.len < 2) {
-        return null;
-    }
-
-    const filename = args[1];
-    const cwd = std.fs.cwd();
-    var token_buffer: [256]u8 = undefined;
-    const token = try cwd.readFile(filename, &token_buffer);
-
-    return try allocator.dupe(u8, std.mem.trim(u8,token,"\n\t "));
-}
-
-const TaskTree = struct {
-    const TaskTreeNode = struct {
-        parent: ?usize,
-        character_task: CharacterBrain.CharacterTask,
-        additional_items: BoundedSlotsArray(8) = BoundedSlotsArray(8).init(),
-    };
-
-    const Nodes = std.ArrayList(TaskTreeNode);
-
-    allocator: Allocator,
-    nodes: Nodes,
-    api: *Server,
-
-    pub fn init(allocator: Allocator, api: *Server) TaskTree {
-        return TaskTree{
-            .allocator = allocator,
-            .nodes = Nodes.init(allocator),
-            .api = api
-        };
-    }
-
-    pub fn deinit(self: TaskTree) void {
-        self.nodes.deinit();
-    }
-
-    fn appendNode(self: *TaskTree, node: TaskTreeNode) !usize {
-        try self.nodes.append(node);
-        return self.nodes.items.len-1;
-    }
-
-    fn appendSubTree(self: *TaskTree, code: []const u8, quantity: u64, parent: ?usize) !?usize {
-        if (quantity == 0) return null;
-
-        const item = (try self.api.getItem(code)).?;
-        const item_id = try self.api.getItemId(code);
-
-        const eql = std.mem.eql;
-        if (item.craft) |recipe| {
-            const craft_count = std.math.divCeil(u64, quantity, recipe.quantity) catch unreachable;
-
-            const skill_str = Server.SkillUtils.toString(recipe.skill);
-            const workshop_maps = try self.api.getMaps(.{ .code = skill_str, .type = .workshop });
-            defer workshop_maps.deinit();
-
-            if (workshop_maps.items.len == 0) return error.WorkshopNotFound;
-            if (workshop_maps.items.len > 1) std.log.warn("Multiple workshop locations exist", .{});
-
-            const node_id = try self.appendNode(TaskTreeNode{
-                .parent = parent,
-                .character_task = .{
-                    .craft = .{
-                        .at = workshop_maps.items[0].position,
-                        .target = .{ .id = item_id, .quantity = craft_count }
-                    }
-                }
-            });
-
-            for (recipe.items.slots.constSlice()) |recipe_item| {
-                const recipe_item_code = self.api.getItemCode(recipe_item.id).?;
-                const needed_quantity = recipe_item.quantity * craft_count;
-                const subtree_id = try self.appendSubTree(recipe_item_code, needed_quantity, node_id);
-
-                // The target item can not be currently produced.
-                if (subtree_id == null) {
-                    var node = &self.nodes.items[node_id];
-                    try node.additional_items.add(recipe_item.id, needed_quantity);
-                }
-            }
-
-            return node_id;
-        } else if (item.type == .resource) {
-            if (eql(u8, item.subtype, "mining") or eql(u8, item.subtype, "fishing") or eql(u8, item.subtype, "woodcutting")) {
-                const resources = try self.api.getResources(.{ .drop = code });
-                defer resources.deinit();
-
-                if (resources.items.len == 0) return error.ResourceNotFound;
-                if (resources.items.len > 1) std.log.warn("Multiple resources exist for target item", .{});
-                const resource_code = resources.items[0].code;
-
-                const resource_maps = try self.api.getMaps(.{ .code = resource_code });
-                defer resource_maps.deinit();
-
-                if (resource_maps.items.len == 0) return error.MapNotFound;
-                if (resource_maps.items.len > 1) std.log.warn("Multiple map locations exist for resource", .{});
-                const resource_map = resource_maps.items[0];
-
-                return try self.appendNode(TaskTreeNode{
-                    .parent = parent,
-                    .character_task = .{
-                        .gather = .{
-                            .at = resource_map.position,
-                            .target = .{ .id = item_id, .quantity = quantity }
-                        }
-                    }
-                });
-            } else if (eql(u8, item.subtype, "mob")) {
-                const monsters = try self.api.getMonsters(.{ .drop = code });
-                defer monsters.deinit();
-
-                if (monsters.items.len == 0) return error.ResourceNotFound;
-                if (monsters.items.len > 1) std.log.warn("Multiple monsters exist for target item", .{});
-                const monster_code = monsters.items[0].code;
-
-                const resource_maps = try self.api.getMaps(.{ .code = monster_code });
-                defer resource_maps.deinit();
-
-                // This monster currently doesn't exist on the map. Probably only spawns in certain situations.
-                if (resource_maps.items.len == 0) return null;
-
-                if (resource_maps.items.len > 1) std.log.warn("Multiple map locations exist for monster", .{});
-                const resource_map = resource_maps.items[0];
-
-                return try self.appendNode(TaskTreeNode{
-                    .parent = parent,
-                    .character_task = .{
-                        .fight = .{
-                            .at = resource_map.position,
-                            .target = .{ .id = item_id, .quantity = quantity }
-                        }
-                    }
-                });
-            }
-        }
-
-        return null;
-    }
-
-    fn listByParent(self: *const TaskTree, parent: ?usize) !std.ArrayList(usize) {
-        var found_nodes = std.ArrayList(usize).init(self.allocator);
-        for (0.., self.nodes.items) |i, node| {
-            if (node.parent == parent) {
-                try found_nodes.append(i);
-            }
-        }
-        return found_nodes;
-    }
-
-    fn listNextTasks(self: *const TaskTree) !std.ArrayList(*CharacterBrain.CharacterTask) {
-        var next_tasks = std.ArrayList(*CharacterBrain.CharacterTask).init(self.allocator);
-        errdefer next_tasks.deinit();
-
-        for (0.., self.nodes.items) |i, *node| {
-            var child_nodes = try self.listByParent(i);
-            defer child_nodes.deinit();
-
-            var can_be_started = true;
-            for (child_nodes.items) |child_node_id| {
-                var child_node = self.nodes.items[child_node_id];
-                if (!child_node.character_task.isComplete()) {
-                    can_be_started = false;
-                    break;
-                }
-            }
-
-            if (can_be_started) {
-                try next_tasks.append(&node.character_task);
-            }
-        }
-
-        return next_tasks;
-    }
-
-    pub fn format(
-        self: TaskTree,
-        comptime fmt: []const u8,
-        options: std.fmt.FormatOptions,
-        writer: anytype,
-    ) !void {
-        _ = fmt;
-        _ = options;
-
-        var root_nodes = try self.listByParent(null);
-        defer root_nodes.deinit();
-
-        for (root_nodes.items) |root_node| {
-            try self.formatNode(root_node, 0, writer);
-        }
-    }
-
-    fn formatNode(self: TaskTree, node_id: usize, level: u32, writer: anytype) !void {
-        const node = self.nodes.items[node_id];
-        try writer.writeBytesNTimes("  ", level);
-        switch (node.character_task) {
-            .fight => |args| {
-                const item = self.api.getItemCode(args.target.id).?;
-                try writer.print("Task{{ .fight = {{ \"{s}\" x {} }}, .at = {} }}\n", .{item, args.target.quantity, args.at});
-            },
-            .gather => |args| {
-                const item = self.api.getItemCode(args.target.id).?;
-                try writer.print("Task{{ .gather = {{ \"{s}\" x {} }}, .at = {} }}\n", .{item, args.target.quantity, args.at});
-            },
-            .craft => |args| {
-                const item = self.api.getItemCode(args.target.id).?;
-                try writer.print("Task{{ .craft = {{ \"{s}\" x {} }}, .at = {} }}\n", .{item, args.target.quantity, args.at});
-            },
-        }
-
-        var child_nodes = try self.listByParent(node_id);
-        defer child_nodes.deinit();
-
-        for (child_nodes.items) |child_node| {
-            try self.formatNode(child_node, level + 1, writer);
-        }
-        for (node.additional_items.slots.constSlice()) |slot| {
-            const item_code = self.api.getItemCode(slot.id).?;
-            try writer.writeBytesNTimes("  ", level+1);
-            try writer.print("+ {{ \"{s}\" x {} }}\n", .{item_code, slot.quantity});
-        }
-    }
-};
-
-pub fn main() !void {
-    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
-    defer _ = gpa.deinit();
-    const allocator = gpa.allocator();
-
-    var api = try Server.init(allocator);
-    defer api.deinit();
-
-    const token = (try getAPITokenFromArgs(allocator)) orelse return error.MissingToken;
-    defer allocator.free(token);
-
-    try api.setToken(token);
-
-    std.log.info("prefetching static data", .{});
-    try api.prefetch();
-
-    var goal_manager = GoalManager.init(&api, allocator);
-    defer goal_manager.deinit();
-
-    const chars = try api.listMyCharacters();
-    defer chars.deinit();
-
-    for (chars.items) |char| {
-        try goal_manager.addCharacter(char.name);
-    }
-
-    var task_tree = TaskTree.init(allocator, &api);
-    defer task_tree.deinit();
-
-    // _ = try task_tree.appendSubTree("wooden_staff", 5, null);
-    _ = try task_tree.appendSubTree("wooden_shield", 5, null);
-
-    std.debug.print("{}", .{task_tree});
-
-    var default_prng = std.rand.DefaultPrng.init(@bitCast(std.time.timestamp()));
-    var random = default_prng.random();
-
-    std.log.info("Starting main loop", .{});
-    while (true) {
-        goal_manager.runNextAction() catch |err| switch (err) {
-            Server.APIError.ServerUnavailable => {
-                // If the server is down, wait for a moment and try again.
-                std.time.sleep(std.time.ns_per_min * 5);
-                continue;
-            },
-
-            // TODO: Log all other error to a file or something. So it could be review later on.
-            else => return err
-        };
-
-        for (goal_manager.characters.items) |*brain| {
-            if (brain.action_queue.items.len > 0) continue;
-
-            if (brain.isTaskFinished()) {
-                if (try brain.depositItemsToBank(&api)) {
-                    continue;
-                }
-                brain.task = null;
-            }
-
-            if (brain.task == null) {
-                var next_tasks = try task_tree.listNextTasks();
-                defer next_tasks.deinit();
-
-                if (next_tasks.items.len > 0) {
-                    const next_task_index = random.intRangeLessThan(usize, 0, next_tasks.items.len);
-                    brain.task = next_tasks.items[next_task_index];
-                }
-            }
-
-            try brain.performTask(&api);
-        }
-    }
-}