// Copyright 2014 by Sascha L. Teichmann
// Use of this source code is governed by the MIT license
// that can be found in the LICENSE file.

package main

import (
	"fmt"
	"image/color"
	"log"
	"os"
	"path/filepath"
	"sync"

	"bitbucket.org/s_l_teichmann/mtredisalize/common"
)

const (
	width          = 18
	height         = 18
	baseLevelDir   = "8"
	yOrderCapacity = 512
)

// To scan the whole height in terms of the y coordinate
// the database is queried in height units defined in the yRanges table.
var yRanges = [][]int16{
	{1024, 1934},
	{256, 1023},
	{128, 255},
	{64, 127},
	{32, 63},
	{16, 31},
	{8, 15},
	{4, 7},
	{2, 3},
	{0, 1},
	{-1, 0},
	{-4, -2},
	{-8, -5},
	{-16, -9},
	{-32, -17},
	{-64, -33},
	{-128, -65},
	{-256, -129},
	{-1024, -257},
	{-1936, -1025}}

type blockPos struct {
	x, z int16
	j, i int
}

type baseLevelWorker struct {
	client   *common.RedisClient
	colors   *common.Colors
	renderer *common.Renderer
	yOrder   *common.YOrder
	baseDir  string
}

func newBaseLevelWorker(client *common.RedisClient,
	colors *common.Colors, baseDir string) *baseLevelWorker {
	renderer := common.NewRenderer(width, height)
	return &baseLevelWorker{
		client:   client,
		colors:   colors,
		baseDir:  baseDir,
		renderer: renderer,
		yOrder:   common.NewYOrder(renderer, yOrderCapacity)}
}

func (blw *baseLevelWorker) close() error {
	return blw.client.Close()
}

func (blw *baseLevelWorker) createTile(x, z int16, i, j int) {
	blw.renderer.Reset()
	blw.renderer.SetPos(x, z)
	blw.yOrder.Reset()

	drawBlock := func(block *common.Block) {
		if err := blw.yOrder.RenderBlock(block, blw.colors.NameIndex); err != nil {
			log.Printf("WARN: rendering block failed: %s", err)
		}
	}

	var c1, c2 common.Coord

	nareas := make([]common.Area, 0, width*height/2)
	oareas := make([]common.Area, 1, width*height/2)

	oareas[0] = common.Area{
		X1: 0, Z1: 0,
		X2: int16(width) - 1, Z2: int16(height) - 1}

	var err error

	for _, yRange := range yRanges {
		c1.Y = yRange[0]
		c2.Y = yRange[1]

		nareas = blw.renderer.UncoveredAreas(nareas, oareas)

		if len(nareas) == 0 {
			break
		}

		for _, area := range nareas {
			c1.X = area.X1 + x
			c1.Z = area.Z1 + z
			c2.X = area.X2 + x
			c2.Z = area.Z2 + z
			query := common.Cuboid{P1: c1, P2: c2}
			if err = blw.client.QueryCuboid(query, drawBlock); err != nil {
				log.Printf("WARN: query failed: %s", err)
				return
			}
			if err = blw.yOrder.Drain(blw.colors.NameIndex); err != nil {
				log.Printf("WARN: rendering block failed: %s", err)
			}
		}
		oareas, nareas = nareas, oareas[0:0]
	}

	image := blw.renderer.CreateShadedImage(
		16, 16, (width-2)*16, (height-2)*16,
		blw.colors.Colors, color.RGBA{R: 0xff, G: 0xff, B: 0xff, A: 0xff})

	path := filepath.Join(blw.baseDir, fmt.Sprintf("%d", i), fmt.Sprintf("%d.png", j))

	log.Printf("Writing (%d, %d) (%d, %d)", i, j, x, z)

	if err = common.SaveAsPNG(path, image); err != nil {
		log.Fatalf("writing image failed: %s", err)
	}
}

func (blw *baseLevelWorker) run(jobs chan blockPos, done *sync.WaitGroup) {
	defer done.Done()
	for job := range jobs {
		blw.createTile(job.x-1, job.z-1, job.i, job.j)
	}
}

func order(a, b int) (int, int) {
	if a < b {
		return a, b
	}
	return b, a
}

func createBaseLevel(
	address string,
	xMin, zMin, xMax, zMax int,
	colorsFile, outDir string,
	numWorkers int) (err error) {

	var colors *common.Colors

	if colors, err = common.ParseColors(colorsFile); err != nil {
		return
	}

	baseDir := filepath.Join(outDir, baseLevelDir)
	if err = os.MkdirAll(baseDir, os.ModePerm); err != nil {
		return
	}

	jobs := make(chan blockPos)
	var done sync.WaitGroup

	for i := 0; i < numWorkers; i++ {
		var client *common.RedisClient
		if client, err = common.NewRedisClient("tcp", address); err != nil {
			return
		}
		done.Add(1)
		blw := newBaseLevelWorker(client, colors, baseDir)
		defer blw.close()
		go blw.run(jobs, &done)
	}

	zMin, zMax = order(zMin, zMax)

	for x, i := int16(xMin), 0; x <= int16(xMax); x += 16 {
		xDir := filepath.Join(baseDir, fmt.Sprintf("%d", i))
		log.Printf("creating dir: %s", xDir)
		if err = os.MkdirAll(xDir, os.ModePerm); err != nil {
			log.Fatalf("Cannot create directory '%s': %s", xDir, err)
		}
		for z, j := int16(zMin), 0; z <= int16(zMax); z += 16 {
			jobs <- blockPos{x: x, z: z, i: i, j: j}
			j++
		}
		i++
	}
	close(jobs)

	done.Wait()

	return
}