import { ctx, ResourceCacheFactory } from './canvas'
import Resource from './resource'

const cacheFactory = new ResourceCacheFactory()

class TileMap {
  constructor (image, rows) {
    this._src = image
    this.rows = rows
    this.defs = {}
  }

  get height () {
    return this.image.height
  }

  get width () {
    return this.image.width
  }

  get tile () {
    return this.width / this.rows
  }

  get image () {
    return Resource.loadImage(this._src, true)
  }

  tileAt (i) {
    return { x: (i % this.rows) * this.tile, y: Math.floor(i / this.rows) * this.tile }
  }

  define (tile, index) {
    if (typeof tile === 'object') {
      this.defs = Object.assign(this.defs, tile)
      return
    }
    this.defs[tile] = index
  }

  indexOf (tile) {
    return this.defs[tile] || null
  }

  positionOf (tile) {
    return this.tileAt(this.indexOf(tile))
  }
}

class TileChunk {
  constructor (ix, iy, size = 16, tileSize = 16) {
    this.x = ix
    this.y = iy
    this.size = size
    this.tile = tileSize
    this.tiles = []
    this.dirty = true
    this.img = null
    this._updated = false
  }

  generateMap (tileMap, heightMap) {
    for (let i = 0; i < this.size * this.size; i++) {
      let tileCoords = this.toXY(i)
      let tileAbs = this.toAbs(tileCoords)
      let y = Math.ceil(heightMap.getHeight(tileAbs.x) * 5 / 2) - 4
      if (tileAbs.y < y) {
        this.tiles.push(-1)
        continue
      }
      if (tileAbs.y === y) {
        this.tiles.push(tileMap.indexOf('GRASS_TOP'))
        continue
      }
      if (tileAbs.y < y + 10) {
        this.tiles.push(tileMap.indexOf('DIRT'))
        continue
      }
      this.tiles.push(tileMap.indexOf('STONE'))
    }
  }

  tileAt (i) {
    return this.tiles[i]
  }

  tileAtXY (x, y) {
    return this.tileAt(x + this.size * y)
  }

  toXY (i) {
    return { x: i % this.size, y: Math.floor(i / this.size) }
  }

  toAbs (x, y) {
    if (typeof x === 'object') {
      y = x.y
      x = x.x
    }
    return { x: this.x * this.size + x, y: this.y * this.size + y }
  }

  get absPos () {
    return { x: this.x * this.size * this.tile, y: this.y * this.size * this.tile }
  }

  draw (view, map) {
    // Create a cached image of the chunk
    if (this.dirty || !this.img) {
      cacheFactory.prepare(this.size * this.tile, this.size * this.tile)
      for (let i in this.tiles) {
        let tilei = this.tiles[i]
        if (tilei === -1) continue
        let coords = this.toXY(parseInt(i))
        let tileCoords = map.tileAt(tilei)
        cacheFactory.ctx.drawImage(map.image, tileCoords.x, tileCoords.y, map.tile, map.tile,
          coords.x * this.tile, coords.y * this.tile, this.tile, this.tile)
      }
      this.img = cacheFactory.capture()
      this.dirty = false
      this._updated = true
      return
    }
    // Draw the cached image
    let p = this.absPos
    ctx.drawImage(this.img, p.x - view.x, p.y - view.y)
  }

  update (dt) {

  }
}

class World {
  constructor (heightMap, tileMaps, chunkSize = 16, tileSize = 16) {
    this.heightMap = heightMap
    this.chunkSize = chunkSize
    this.tileSize = tileSize
    this.tileMaps = tileMaps
    this.chunks = []

    // Debug info
    this._lastDrawCount = 0
    this._lastUpdateCount = 0
  }

  getChunk (x, y) {
    for (let i in this.chunks) {
      let chunk = this.chunks[i]
      if (chunk && chunk.x === x && chunk.y === y) return chunk
    }
    return null
  }

  update (dt, vp) {
    let posPoint = vp.chunkIn(this.chunkSize * this.tileSize)
    for (let x = posPoint.x - 4; x < posPoint.x + 5; x++) {
      for (let y = posPoint.y - 4; y < posPoint.y + 5; y++) {
        if (x < 0 || y < 0) continue
        let exists = this.getChunk(x, y)
        if (!exists) {
          let n = new TileChunk(x, y, this.chunkSize, this.tileSize)
          n.generateMap(this.tileMaps.GROUND, this.heightMap)
          this.chunks.push(n)
          break
        }
      }
    }

    for (let i in this.chunks) {
      this.chunks[i].update(dt)
    }
  }

  draw (vp) {
    this._lastDrawCount = 0
    this._lastUpdateCount = 0
    for (let i in this.chunks) {
      let chunk = this.chunks[i]
      let absPos = chunk.absPos
      let chunkSize = chunk.size * this.tileSize
      if (absPos.x > vp.x + vp.width || absPos.x + chunkSize < vp.x ||
        absPos.y > vp.y + vp.height || absPos.y + chunkSize < vp.y) continue
      chunk._updated = false
      chunk.draw(vp, this.tileMaps.GROUND)
      if (chunk._updated) this._lastUpdateCount++
      this._lastDrawCount++
    }
  }
}

export { TileMap, TileChunk, World }