package tile

import "fmt"
import "gitlab.com/beoran/ebsgo/monolog"
// import "os"
// import "math"

import "gitlab.com/beoran/al5go/al"
import "gitlab.com/beoran/ebsgo/engine/geometry"

const TILE_W = 32
const TILE_H = 32

var showSolid = false;


/** A tile set */
type Set struct { 
  Tiles     []Tile
  Sheet     * al.Bitmap
  W         int // Width, in tiles
  H         int // Height, in tiles
  TileW     int
  TileH     int
  FirstGID  int  /* Offset of tile set in TMX map file. Used to  correct tile offsets. */
};



/** A Tiled-style animation frame of a tile. */
type Frame struct {
    Index int  /* Tile set index for this frame of animation. */
    Duration float64 /* Duration of the frame in s. */
}

/** 
* A single tile from a tile map.
* Tiles can be animated. This works like this: a tile has an animation
* pointer and offset which points to the next tile to be drawn in the tileset.
*/
type Tile struct {
  Tileset       * Set   /* Tileset this tile belongs to */
  Index           int   /* Index in the tile set. */  
  Flags           int  /* Information about the tile's properties. */
  Kind            int

  /* Offset to the tile to skip to when animating. If this is
  0 the tile is not animated. If nonzero, the tile will skip to
  the tile in the same tile set set with index index + anim.
  May be negative to "roll back" an animation to it's begin. */  
  Anim            int
  
  /** For unanimated tiles, active is set to the index of the tile itself.
   For animated tiles, it is set to the index of tile that currently should
   be displayed in stead of this tile due to animation.
  */
  Active        int 
  
  Wait          float64
  /* Time in s to wait before jumping to the next frame of this tile. */  
  Time          float64
  /* Time since last animation in s. */
  Position      geometry.Vector
  /* Automatic blending activation and priority. */
  Blend         int
  /* Mask number to use for automatic blending, if any. */
  BlendMask     int
  /* Automatic lighting activation flag. */
  Light         int
  LightMask     int
  /* Automatic shadow activation flag. */
  Shadow        int
  /* Automatic shadow mask number. */
  ShadowMask    int
  /* Tiled-style animation frames. */
  Frames        []*Frame
  /* Active frame for TMX-style animations. */
  ActiveFrame   int
};

/* NOTE: Tiles could be implemented using sub bitmaps as they seem to be
* slightly faster if they are preallocated. however the speed gain would
* be around 2%, so it's not a priority yet. It could simplify some of
* the code, though.
*/


func NewSet(sheet * al.Bitmap, tile_w, tile_h, firstgid int) * Set {
    if sheet == nil {
        return nil
    }
    set := &Set{}
    set.Sheet       = sheet
    set.TileW       = tile_w
    set.TileH       = tile_h
    set.FirstGID    = firstgid
    set.W           = sheet.Width() / set.TileW
    set.H           = sheet.Height() / set.TileH
    size           := set.W * set.H
    set.Tiles       = make([]Tile, size)
    for i := 0 ; i < size; i ++ {
        set.Tiles[i].Init(set, i)
    }
    return set
}

func (set * Set) Close() {
    if set.Sheet != nil {
        set.Sheet.Destroy()
        set.Sheet = nil
    }
}

func (tile * Tile) Init(set * Set, index int) {
    tile.Tileset    = set
    tile.Index      = index
    tile.Active     = index
    tile.Wait       = 0.25
    tile.Recalculate()
} 

func (tile Tile) SheetY(set * Set) int {
    return (tile.Active / set.W) * set.TileH
}

func (tile Tile) SheetX(set * Set) int {
    return (tile.Active % set.W) * set.TileW
}


/** Recalculates the tile's position (now) in it's tile set. */
func (tile * Tile) Recalculate() {
    if nil == tile.Tileset {
        return
    }
    
    x := float32(tile.SheetX(tile.Tileset))
    y := float32(tile.SheetY(tile.Tileset))
        
    tile.Position = geometry.NewVector(x, y)
}


func (set Set) Tile(index int) * Tile {
    if index >= 0 && index <= len(set.Tiles) {
        return &set.Tiles[index]
    } 
    return nil
}


/** Tile types */
const (
    TILE_NONE   = 0
    TILE_WALL   = iota
    TILE_WATER  = iota
    TILE_LEDGE  = iota
    TILE_STAIR  = iota
    TILE_PUSH   = iota
    TILE_NORTH  = iota
    TILE_SOUTH  = iota
    TILE_EAST   = iota
    TILE_WEST   = iota
    TILE_UP     = iota
    TILE_DOWN   = iota
    TILE_ICE    = iota
 )
 
 


/* Helper lookup table for the tile flag names */
var FlagNames map[string]uint = map[string]uint {
  "wall" : TILE_WALL  ,
  "water": TILE_WATER ,
  "ledge": TILE_LEDGE ,
  "stair": TILE_STAIR ,
  "push" : TILE_PUSH  ,
  "north": TILE_NORTH ,
  "south": TILE_SOUTH ,
  "east" : TILE_EAST  ,
  "west" : TILE_WEST  ,
  "up"   : TILE_UP    ,
  "down" : TILE_DOWN  ,
  "ice"  : TILE_ICE   ,
}


/** Sets a tile's flags from a property string.
* This uses an internal lookup table.
*/
func (tile * Tile) SetProperty(property string) {
    val, ok := FlagNames[property];
    if (ok) {   
        tile.Flags |= (1 << val)
    }
}

func (tile * Tile) HasFlag(flag uint) bool {
    return (tile.Flags & (1 << flag)) == (1 << flag)
}

func (tile * Tile) IsWall() bool {
    return tile.HasFlag(TILE_WALL)
}

/** Initializes a tile's frame of animation. */
func (frame * Frame) Init(index int, duration float64) {
    frame.Index     = index
    frame.Duration  = duration
}

func (frame Frame) String() string {
    return fmt.Sprintf("frame: %d", frame.Index)
}

/** Gets the nth frame of Tiled style animations for this tile 
 * or NULL if no such animation frame. */
func (tile Tile) Frame(index int)  * Frame {
    if nil == tile.Frames{ 
       return nil
    } else { 
        return tile.Frames[index]
    }
} 

/** Gets the amount of Tiled style animations for this tile, or 0 if none. */
func (tile Tile) FrameCount() int {
    if nil == tile.Frames { 
       return 0
    } else { 
        return len(tile.Frames)
    }
}

/** Adds a Tiled-style animation frame to the tile. */
func (tile * Tile) AddAnimationFrame(index int, duration float64) (frame * Frame) {
    frame       = &Frame{}
    tile.Frames = append(tile.Frames, frame)
    frame.Init(index, duration)
    return frame
}
  

/** Rewinds a tile's animations. */
func (tile * Tile) RewindAnimations() {
  tile.Active       = tile.Index
  tile.ActiveFrame  = 0
  // Finally recalculate tile position.
  tile.Recalculate()
}


/**  Updates a tile to animate it using TMX style animation. */
func (tile * Tile) UpdateAnimation(dt float64) {
  active := 0;

  frame := tile.Frame(tile.ActiveFrame)
  if nil == frame { /* Animation overshot itself */
    tile.ActiveFrame = 0
    frame = tile.Frame(tile.ActiveFrame)
    if nil == frame { /* Tile has no frames at all. */
         return
    }
  }
  
  /* monolog.Log("TILE", "Animation for tile: %d %d %f %f\n", 
    tile.ActiveFrame, frame.Index, frame.Duration, tile.Time) */

  
  tile.Time += dt // advance animation time of tile. 
  // Don't animate if not enough time has passed
  if tile.Time < (frame.Duration * 10.0) {
      return
  }
  // advance the animation frame, loop it around if needed. 
  tile.ActiveFrame++
  if tile.ActiveFrame >= tile.FrameCount() {
    tile.ActiveFrame = 0
  }
  // Get new tile frame
  frame = tile.Frame(tile.ActiveFrame);
  // If we get here, reset animation time.

  tile.Time     = 0.0
  if nil == frame {
       return
  }
  
  monolog.Log("TILE", "Animation for tile: %d %d %d %d %v\n", 
    tile.ActiveFrame, frame.Index, frame.Duration, tile.Time, tile.Frames)

  // Get the active tile to use from the animation frame
  active   = frame.Index
  aidtile := tile.Tileset.Tile(active);
  // Check if there is such a tile.
  if nil == aidtile {
      return
  }
  // If there is such a tile, change the active tile index of this tile.
  tile.Active = active
  // Finally recalculate tile position.
  tile.Recalculate()
  monolog.Log("TILE", "Updated animation for tile: %d %d\n", tile.Active, frame.Index)
}

/* Animates the tile. Animates the tile if it has animation frames. */
func (tile * Tile) Update(dt float64) {
  if nil != tile.Frames {
      tile.UpdateAnimation(dt)
  } 
} 


/** Updates all tiles in a tile set so they all get animated. */
func (set * Set) Update(dt float64) {
  if nil == set.Tiles {
       return
  }
  
  for i := 0 ; i < len(set.Tiles); i ++ {
        tile := &set.Tiles[i]
        tile.Update(dt)
  }
} 

/** Recalculates all tiles in a tile set so they all get the rght position. */
func (set * Set) Recalculate() {
  if nil == set.Tiles {
       return
  }
  
  for i := 0 ; i < len(set.Tiles); i ++ {
        tile := &set.Tiles[i]
        tile.Recalculate()
  }
} 


/** Draw a tile to the current active drawing target at the
given coordinates. Does nothing if tile is NULL.  */
func (tile Tile) Draw(x, y float32, drawflags int) {  
  set   := tile.Tileset
  sheet := set.Sheet
  dx    := float32(x)
  dy    := float32(y) 
  sx    := float32(tile.Position.X)
  sy    := float32(tile.Position.Y)
  sw    := float32(set.TileW)
  sh    := float32(set.TileH)
  sheet.DrawRegion(sx, sy, sw, sh, dx, dy, drawflags);
  // debugging solid tiles
  if showSolid { 
    if (tile.Flags & (1<<TILE_WALL)) == (1<<TILE_WALL) {
        dcolor := al.MapRGB(0xee, 0xee, 0x00)
        al.DrawRectangle(dx, dy, dx+sw, dy+sh, dcolor, 2);
    }
  }
}

/* Used for drawing masked tiles. */
var tileMaskBuffer * al.Bitmap

/** Draw a tile into the given bitmap, which should be of size TILE_W, TILE_H 
 * applying the given mask bitmap, where the mask will 
be flipped and rotated as per the given mask_flags. The mask bitmap
should be white, but with different alpha levels on the white 
which will be applied as the mask. Does nothing if tile is NULL.  
This requires al_hold_bitmap_drawing to be turned off!
*/
func (tile * Tile) DrawMaskedTo(result * al.Bitmap, mask * al.Bitmap, angle float32, mask_flags int) {
  /* This function need a mask buffer. */
  
  /* Create a 32x32 tile bitmap that will be reused thanks to 
   it being static. And leaked at program shutdown, but I don't care :p. */
  if nil == tileMaskBuffer { 
    bmpflags      := al.NewBitmapFlags()
    al.SetNewBitmapFlags(al.CONVERT_BITMAP)    
    tileMaskBuffer = al.CreateBitmap(TILE_W, TILE_H)
    al.SetNewBitmapFlags(bmpflags)
  } 
  
  /* Keep the target bitmap. */
  target := al.TargetBitmap()
  
  /* Copy the tile into the buffer.  */
  al.SetTargetBitmap(tileMaskBuffer)
  set    := tile.Tileset
  sheet  := set.Sheet
  dx     := float32(0.0)
  dy     := float32(0.0)
  sx     := float32(tile.Position.X)
  sy     := float32(tile.Position.Y)
  sw     := float32(set.TileW )
  sh     := float32(set.TileH )
  /* Set blender to copy mode. */
  al.SetBlender(al.ADD, al.ONE, al.ZERO) 
  sheet.DrawRegion(sx, sy, sw, sh, 0, 0, 0);
  
  /* Draw the mask over the tile, taking the alpha of the mask  */
  al.SetBlender(al.ADD, al.ZERO, al.ALPHA) 
  mask.Draw(0, 0, mask_flags)
  
  /* Restore normal Allegro blending. */
  al.SetBlender(al.ADD, al.ONE, al.INVERSE_ALPHA) 

  sx = 0.0
  sy = 0.0
  if (angle != 0.0) {
    sx = float32(set.TileW) / 2.0
    sy = float32(set.TileH) / 2.0
    dx += sx
    dy += sy
  }
  
  /* Draw the tile mask buffer to the result bitmap */
  al.SetTargetBitmap(result)
  tileMaskBuffer.DrawRotated(sx, sy, dx, dy, angle, 0)
  /* And restore the target bitmap. */ 
  al.SetTargetBitmap(target)
}