import { FloorplanAction, FloorplanState, Tile } from './types';
import { MAX_NUM_TILE_PER_AXIS, EMPTY_DOOR, MIN_WALL_HEIGHT, MAX_WALL_HEIGHT } from './constants';
import { parseTilemap } from './encoding';

export const initialState: FloorplanState = {
    tiles: [],
    door: { ...EMPTY_DOOR },
    thickness: { wall: 1, floor: 1 },
    wallHeight: -1,
    brush: { h: 0, action: 'SET' },
    selection: new Set<`${number},${number}`>(),
    squareSelect: false,
    lease: { holder: null, me: false, expiresAt: null },
    seq: 0
};

const clampHeight = (h: number): number => Math.max(0, Math.min(26, h | 0));
const clamp64 = (n: number): number => Math.max(0, Math.min(MAX_NUM_TILE_PER_AXIS - 1, n | 0));

const ensureRect = (tiles: Tile[][], rows: number, cols: number): Tile[][] =>
{
    const tRows = Math.min(MAX_NUM_TILE_PER_AXIS, Math.max(rows, tiles.length));
    const tCols = Math.min(MAX_NUM_TILE_PER_AXIS, Math.max(cols, tiles[0]?.length ?? 0));
    if(tRows === tiles.length && (tiles[0]?.length ?? 0) === tCols) return tiles;
    const next: Tile[][] = [];
    for(let r = 0; r < tRows; r++)
    {
        const src = tiles[r] ?? [];
        const row: Tile[] = [];
        for(let c = 0; c < tCols; c++)
        {
            row.push(src[c] ?? { h: 0, blocked: true });
        }
        next.push(row);
    }
    return next;
};

const setTile = (tiles: Tile[][], row: number, col: number, tile: Tile): Tile[][] =>
{
    const current = tiles[row]?.[col];
    if(current && current.h === tile.h && current.blocked === tile.blocked) return tiles;
    const next = tiles.map((r, ri) => ri === row ? r.map((t, ci) => ci === col ? tile : t) : r);
    return next;
};

export const reducer = (state: FloorplanState, action: FloorplanAction): FloorplanState =>
{
    switch(action.type)
    {
        case 'PAINT_TILE':
        {
            const row = clamp64(action.row);
            const col = clamp64(action.col);
            const tiles = ensureRect(state.tiles, row + 1, col + 1);
            const target = { h: clampHeight(action.h), blocked: false };
            const next = setTile(tiles, row, col, target);
            if(next === tiles && tiles === state.tiles) return state;
            return { ...state, tiles: next };
        }
        case 'ERASE_TILE':
        {
            const row = action.row | 0;
            const col = action.col | 0;
            if(row < 0 || col < 0 || row >= state.tiles.length || col >= (state.tiles[0]?.length ?? 0)) return state;
            const current = state.tiles[row][col];
            const target = { h: current.h, blocked: true };
            const next = setTile(state.tiles, row, col, target);
            if(next === state.tiles) return state;
            return { ...state, tiles: next };
        }
        case 'ADJUST_HEIGHT':
        {
            const row = action.row | 0;
            const col = action.col | 0;
            if(row < 0 || col < 0 || row >= state.tiles.length || col >= (state.tiles[0]?.length ?? 0)) return state;
            const current = state.tiles[row][col];
            if(current.blocked) return state;
            const newH = clampHeight(current.h + action.delta);
            if(newH === current.h) return state;
            const next = setTile(state.tiles, row, col, { h: newH, blocked: false });
            return { ...state, tiles: next };
        }
        case 'SET_DOOR':
        {
            const x = clamp64(action.x);
            const y = clamp64(action.y);
            if(state.door.x === x && state.door.y === y) return state;
            return { ...state, door: { ...state.door, x, y } };
        }
        case 'SET_DOOR_DIR':
        {
            if(state.door.dir === action.dir) return state;
            return { ...state, door: { ...state.door, dir: action.dir } };
        }
        case 'SET_THICKNESS':
        {
            const wall = action.wall ?? state.thickness.wall;
            const floor = action.floor ?? state.thickness.floor;
            if(wall === state.thickness.wall && floor === state.thickness.floor) return state;
            return { ...state, thickness: { wall, floor } };
        }
        case 'SET_WALL_HEIGHT':
        {
            const value = Math.max(MIN_WALL_HEIGHT, Math.min(MAX_WALL_HEIGHT, action.value | 0));
            if(value === state.wallHeight) return state;
            return { ...state, wallHeight: value };
        }
        case 'BRUSH_SET':
        {
            const h = action.h ?? state.brush.h;
            const act = action.action ?? state.brush.action;
            if(h === state.brush.h && act === state.brush.action) return state;
            return { ...state, brush: { h: clampHeight(h), action: act } };
        }
        case 'SELECT_ALL':
        {
            const sel = new Set<`${number},${number}`>();
            for(let r = 0; r < MAX_NUM_TILE_PER_AXIS; r++)
            {
                for(let c = 0; c < MAX_NUM_TILE_PER_AXIS; c++)
                {
                    sel.add(`${r},${c}`);
                }
            }
            return { ...state, selection: sel };
        }
        case 'CLEAR_SELECTION':
            return state.selection.size === 0 ? state : { ...state, selection: new Set() };
        case 'SELECT_RECT':
        {
            const [ r0, c0 ] = action.from;
            const [ r1, c1 ] = action.to;
            const rMin = Math.max(0, Math.min(r0, r1));
            const rMax = Math.min(MAX_NUM_TILE_PER_AXIS - 1, Math.max(r0, r1));
            const cMin = Math.max(0, Math.min(c0, c1));
            const cMax = Math.min(MAX_NUM_TILE_PER_AXIS - 1, Math.max(c0, c1));
            const sel = new Set<`${number},${number}`>();
            for(let r = rMin; r <= rMax; r++)
            {
                for(let c = cMin; c <= cMax; c++)
                {
                    sel.add(`${r},${c}`);
                }
            }
            return { ...state, selection: sel };
        }
        case 'APPLY_BRUSH_TO_SELECTION':
        {
            if(state.selection.size === 0) return state;
            if(state.brush.action === 'DOOR') return { ...state, selection: new Set() };

            let maxR = -1;
            let maxC = -1;
            for(const key of state.selection)
            {
                const [ rStr, cStr ] = key.split(',');
                const r = parseInt(rStr, 10);
                const c = parseInt(cStr, 10);
                if(r > maxR) maxR = r;
                if(c > maxC) maxC = c;
            }

            let tiles = state.tiles;
            if(state.brush.action === 'SET' && maxR >= 0 && maxC >= 0)
            {
                tiles = ensureRect(tiles, maxR + 1, maxC + 1);
            }

            for(const key of state.selection)
            {
                const [ rStr, cStr ] = key.split(',');
                const row = parseInt(rStr, 10);
                const col = parseInt(cStr, 10);
                const current = tiles[row]?.[col];
                if(!current) continue;

                switch(state.brush.action)
                {
                    case 'SET':
                        tiles = setTile(tiles, row, col, { h: clampHeight(state.brush.h), blocked: false });
                        break;
                    case 'UNSET':
                        if(current.blocked) continue;
                        tiles = setTile(tiles, row, col, { h: current.h, blocked: true });
                        break;
                    case 'UP':
                        if(current.blocked) continue;
                        tiles = setTile(tiles, row, col, { h: clampHeight(current.h + 1), blocked: false });
                        break;
                    case 'DOWN':
                        if(current.blocked) continue;
                        tiles = setTile(tiles, row, col, { h: clampHeight(current.h - 1), blocked: false });
                        break;
                }
            }

            return { ...state, tiles, selection: new Set() };
        }
        case 'SQUARE_SELECT_TOGGLE':
            return { ...state, squareSelect: !state.squareSelect };
        case 'IMPORT_STRING':
        {
            const tiles = parseTilemap(action.raw);
            const next: FloorplanState = { ...state, tiles };
            if(action.door) next.door = action.door;
            if(action.thickness) next.thickness = action.thickness;
            if(action.wallHeight !== undefined) next.wallHeight = Math.max(MIN_WALL_HEIGHT, Math.min(MAX_WALL_HEIGHT, action.wallHeight | 0));
            return next;
        }
        case 'APPLY_REMOTE_DIFF':
        {
            let next: FloorplanState = { ...state, seq: action.seq };
            if(action.diff.tiles)
            {
                let tiles = next.tiles;
                for(const e of action.diff.tiles)
                {
                    tiles = ensureRect(tiles, e.row + 1, e.col + 1);
                    tiles = setTile(tiles, e.row, e.col, { h: clampHeight(e.h), blocked: e.blocked });
                }
                next.tiles = tiles;
            }
            if(action.diff.door) next.door = action.diff.door;
            if(action.diff.thickness) next.thickness = action.diff.thickness;
            if(action.diff.wallHeight !== undefined) next.wallHeight = Math.max(MIN_WALL_HEIGHT, Math.min(MAX_WALL_HEIGHT, action.diff.wallHeight | 0));
            return next;
        }
        case 'APPLY_REMOTE_SNAPSHOT':
        {
            return {
                ...state,
                tiles: parseTilemap(action.raw),
                door: action.door,
                thickness: action.thickness,
                wallHeight: Math.max(MIN_WALL_HEIGHT, Math.min(MAX_WALL_HEIGHT, action.wallHeight | 0)),
                selection: new Set(),
                seq: action.seq
            };
        }
        default:
            return state;
    }
};