const std = @import("std");
const engine = @import("../engine.zig");

pub const Level = struct {
    pub fn Column(comptime Value: type) type {
        return struct {
            const Self = @This();

            values: std.AutoHashMap(i64, Value),

            pub fn init(allocator: std.mem.Allocator) Self {
                return Self{
                    .values = std.AutoHashMap(i64, Value).init(allocator),
                };
            }

            pub fn deinit(self: Self) void {
                self.values.deinit();
            }

            pub fn get(self: Self, row: i64) ?Value {
                return self.values.get(row);
            }

            pub fn set(self: *Self, row: i64, value: Value) !void {
                try self.values.put(row, value);
            }
        };
    }

    pub fn Components(comptime Value: type) type {
        return struct {
            const Self = @This();

            allocator: std.mem.Allocator,
            columns: std.ArrayList(Column(Value)),

            pub fn init(allocator: std.mem.Allocator) Self {
                return Self{
                    .allocator = allocator,
                    .columns = std.ArrayList(Column(Value)).init(allocator),
                };
            }

            pub fn deinit(self: Self) void {
                for (self.columns.items) |item| {
                    item.deinit();
                }
                self.columns.deinit();
            }

            pub fn column(self: Self, i: i64) *Column(Value) {
                return &self.columns.items[@intCast(usize, i)];
            }

            fn ensureColumns(self: *Self, n: usize) !void {
                while (self.columns.items.len < n) {
                    try self.columns.append(Column(Value).init(self.allocator));
                }
            }

            pub fn set(self: *Self, c: i64, r: i64, value: Value) !void {
                try self.ensureColumns(@intCast(usize, c) + 1);
                try self.column(c).set(r, value);
            }
        };
    }

    pub const Tile = enum {
        Grass,
    };

    pub const Collectable = enum {
        Star,
    };

    character: engine.Point,
    tiles: Components(Tile),
    collectables: Components(Collectable),

    pub fn load(allocator: std.mem.Allocator, path: []const u8) !Level {
        const path_ = try std.fs.realpathAlloc(allocator, path);
        defer allocator.free(path_);

        const file = try std.fs.openFileAbsolute(path_, .{ .mode = .read_only });
        defer file.close();

        const data = try file.readToEndAlloc(allocator, 1024 * 1024);
        defer allocator.free(data);

        return try Level.loadFromMemory(allocator, data);
    }

    pub fn loadFromMemory(allocator: std.mem.Allocator, data: []const u8) !Level {
        const n = std.mem.count(u8, data, "\n");
        _ = n;

        var character: ?engine.Point = null;
        var tiles = Components(Tile).init(allocator);
        var collectables = Components(Collectable).init(allocator);

        var lines = std.mem.split(u8, data, "\n");
        var y: i64 = 0;
        while (lines.next()) |line| {
            defer y += 1;

            try tiles.ensureColumns(line.len);
            try collectables.ensureColumns(line.len);

            for (line, 0..) |tile, column| {
                var x = @intCast(i64, column);
                switch (tile) {
                    'P' => character = engine.Point.init(x, y),
                    'S' => try collectables.set(x, y, Collectable.Star),
                    'x' => try tiles.set(x, y, Tile.Grass),
                    else => {},
                }
            }
        }

        return Level{
            .character = character.?,
            .tiles = tiles,
            .collectables = collectables,
        };
    }
};