'use client'

import { create } from 'zustand'
import type { ChunkData, World } from '@/types'
import {
  CHUNK_WIDTH, CHUNK_HEIGHT, CHUNK_DEPTH,
  BLOCK_AIR, MIN_BUILD_HEIGHT,
} from '@/engine/constants'
import { TerrainGenerator } from '@/engine/terrain/generator'
import { NetherGenerator } from '@/engine/terrain/dimensionGenerator'
import { EndGenerator } from '@/engine/terrain/dimensionGenerator'

// ═══════════════════════════════════════════════════════════════
// DIMENSION CONSTANTS
// ═══════════════════════════════════════════════════════════════

const NETHER_CHUNK_HEIGHT = 128
const END_CHUNK_HEIGHT = 128

type DimensionType = 'overworld' | 'nether' | 'end'

function chunkKey(cx: number, cz: number): string {
  return `${cx},${cz}`
}

// ═══════════════════════════════════════════════════════════════
// STORE INTERFACE
// ═══════════════════════════════════════════════════════════════

interface WorldStore {
  world: World | null
  chunks: Map<string, ChunkData>
  dimension: DimensionType
  netherSeed: number
  endSeed: number
  // Generators (lazy-initialized)
  overworldGenerator: TerrainGenerator | null
  netherGenerator: NetherGenerator | null
  endGenerator: EndGenerator | null

  initWorld: (seed: number) => void
  setChunk: (key: string, chunk: ChunkData) => void
  removeChunk: (key: string) => void
  getBlock: (x: number, y: number, z: number) => number
  setBlock: (x: number, y: number, z: number, blockId: number) => void
  updateWorldTime: () => void
  switchDimension: (dimension: string) => void
  generateChunk: (cx: number, cz: number) => ChunkData
  getCurrentChunkHeight: () => number
}

// ═══════════════════════════════════════════════════════════════
// STORE IMPLEMENTATION
// ═══════════════════════════════════════════════════════════════

export const useWorldStore = create<WorldStore>((set, get) => ({
  world: null,
  chunks: new Map(),
  dimension: 'overworld',
  netherSeed: 0,
  endSeed: 0,
  overworldGenerator: null,
  netherGenerator: null,
  endGenerator: null,

  initWorld: (seed: number) => {
    // Derive dimension seeds from main seed
    const netherSeed = (seed * 0x5bd1e995 + 0xDEAD) | 0
    const endSeed = (seed * 0x27d4eb2d + 0xBEEF) | 0

    const world: World = {
      seed,
      time: 6000, // noon
      gameTime: 0,
      spawnPoint: [8, 80, 8],
      weather: { raining: false, thundering: false, rainTime: 0, thunderTime: 0 },
      dimension: 'overworld',
    }

    set({
      world,
      chunks: new Map(),
      dimension: 'overworld',
      netherSeed,
      endSeed,
      overworldGenerator: new TerrainGenerator(seed),
      netherGenerator: new NetherGenerator(netherSeed),
      endGenerator: new EndGenerator(endSeed),
    })
  },

  setChunk: (key, chunk) => {
    const chunks = new Map(get().chunks)
    chunks.set(key, chunk)
    set({ chunks })
  },

  removeChunk: (key) => {
    const chunks = new Map(get().chunks)
    chunks.delete(key)
    set({ chunks })
  },

  getBlock: (x, y, z) => {
    const { dimension } = get()

    // Different height ranges per dimension
    if (dimension === 'overworld') {
      if (y < MIN_BUILD_HEIGHT || y > 319) return BLOCK_AIR
    } else {
      // Nether and End: 0-127
      if (y < 0 || y > 127) return BLOCK_AIR
    }

    const cx = Math.floor(x / CHUNK_WIDTH)
    const cz = Math.floor(z / CHUNK_DEPTH)
    const chunk = get().chunks.get(chunkKey(cx, cz))
    if (!chunk) return BLOCK_AIR

    const lx = ((x % CHUNK_WIDTH) + CHUNK_WIDTH) % CHUNK_WIDTH
    const lz = ((z % CHUNK_DEPTH) + CHUNK_DEPTH) % CHUNK_DEPTH

    // Y offset depends on dimension
    let ly: number
    if (dimension === 'overworld') {
      ly = y - MIN_BUILD_HEIGHT // offset for negative Y
    } else {
      ly = y // nether/end start at 0
    }

    const chunkH = get().getCurrentChunkHeight()
    if (ly < 0 || ly >= chunkH) return BLOCK_AIR

    const idx = lx + lz * CHUNK_WIDTH + ly * CHUNK_WIDTH * CHUNK_DEPTH
    return chunk.blocks[idx] || BLOCK_AIR
  },

  setBlock: (x, y, z, blockId) => {
    const { dimension } = get()

    if (dimension === 'overworld') {
      if (y < MIN_BUILD_HEIGHT || y > 319) return
    } else {
      if (y < 0 || y > 127) return
    }

    const cx = Math.floor(x / CHUNK_WIDTH)
    const cz = Math.floor(z / CHUNK_DEPTH)
    const key = chunkKey(cx, cz)
    const chunk = get().chunks.get(key)
    if (!chunk) return

    const lx = ((x % CHUNK_WIDTH) + CHUNK_WIDTH) % CHUNK_WIDTH
    const lz = ((z % CHUNK_DEPTH) + CHUNK_DEPTH) % CHUNK_DEPTH

    let ly: number
    if (dimension === 'overworld') {
      ly = y - MIN_BUILD_HEIGHT
    } else {
      ly = y
    }

    const chunkH = get().getCurrentChunkHeight()
    if (ly < 0 || ly >= chunkH) return

    const idx = lx + lz * CHUNK_WIDTH + ly * CHUNK_WIDTH * CHUNK_DEPTH
    chunk.blocks[idx] = blockId
    chunk.dirty = true
    chunk.meshVersion++
    set({ chunks: new Map(get().chunks) })
  },

  updateWorldTime: () => {
    const { world } = get()
    if (!world) return
    world.time = (world.time + 1) % 24000
    world.gameTime++
    set({ world })
  },

  switchDimension: (dimension: string) => {
    const { world } = get()
    if (!world) return

    const dim = dimension as DimensionType
    if (dim === get().dimension) return

    // Update the world's dimension
    world.dimension = dim

    // Set spawn point based on dimension
    let spawnPoint: [number, number, number]
    switch (dim) {
      case 'nether':
        spawnPoint = [8, 64, 8]
        break
      case 'end':
        spawnPoint = [0, 65, 0]
        break
      default:
        spawnPoint = [8, 80, 8]
    }

    // Clear all chunks — they will be regenerated by the renderer
    // using the appropriate dimension generator
    set({
      world,
      chunks: new Map(),
      dimension: dim,
    })

    // Update spawn point
    world.spawnPoint = spawnPoint
    set({ world })
  },

  generateChunk: (cx: number, cz: number): ChunkData => {
    const { dimension, overworldGenerator, netherGenerator, endGenerator } = get()

    switch (dimension) {
      case 'nether':
        if (!netherGenerator) {
          // Lazy init if needed
          const { netherSeed } = get()
          const gen = new NetherGenerator(netherSeed)
          set({ netherGenerator: gen })
          return gen.generateChunk(cx, cz)
        }
        return netherGenerator.generateChunk(cx, cz)

      case 'end':
        if (!endGenerator) {
          const { endSeed } = get()
          const gen = new EndGenerator(endSeed)
          set({ endGenerator: gen })
          return gen.generateChunk(cx, cz)
        }
        return endGenerator.generateChunk(cx, cz)

      case 'overworld':
      default:
        if (!overworldGenerator) {
          const { world } = get()
          const seed = world?.seed ?? 12345
          const gen = new TerrainGenerator(seed)
          set({ overworldGenerator: gen })
          return gen.generateChunk(cx, cz)
        }
        return overworldGenerator.generateChunk(cx, cz)
    }
  },

  getCurrentChunkHeight: (): number => {
    const { dimension } = get()
    switch (dimension) {
      case 'nether':
        return NETHER_CHUNK_HEIGHT
      case 'end':
        return END_CHUNK_HEIGHT
      default:
        return CHUNK_HEIGHT
    }
  },
}))