package commands

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"math/rand"
	"net/http"
	"net/url"
	"path"
	"strconv"
	"sync"
	"time"

	"github.com/BattlesnakeOfficial/rules"
	"github.com/google/uuid"
	"github.com/spf13/cobra"
)

type Battlesnake struct {
	URL       string
	Name      string
	ID        string
	API       string
	LastMove  string
	Squad     string
	Character rune
}

type Coord struct {
	X int32 `json:"x"`
	Y int32 `json:"y"`
}

type SnakeResponse struct {
	Id      string  `json:"id"`
	Name    string  `json:"name"`
	Health  int32   `json:"health"`
	Body    []Coord `json:"body"`
	Latency string  `json:"latency"`
	Head    Coord   `json:"head"`
	Length  int32   `json:"length"`
	Shout   string  `json:"shout"`
	Squad   string  `json:"squad"`
}

type BoardResponse struct {
	Height  int32           `json:"height"`
	Width   int32           `json:"width"`
	Food    []Coord         `json:"food"`
	Hazards []Coord         `json:"hazards"`
	Snakes  []SnakeResponse `json:"snakes"`
}

type GameResponseRuleset struct {
	Name    string `json:"name"`
	Version string `json:"version"`
}

type GameResponse struct {
	Id      string              `json:"id"`
	Timeout int32               `json:"timeout"`
	Ruleset GameResponseRuleset `json:"ruleset"`
}

type ResponsePayload struct {
	Game  GameResponse  `json:"game"`
	Turn  int32         `json:"turn"`
	Board BoardResponse `json:"board"`
	You   SnakeResponse `json:"you"`
}

type PlayerResponse struct {
	Move  string `json:"move"`
	Shout string `json:"shout"`
}

type PingResponse struct {
	APIVersion string `json:"apiversion"`
	Author     string `json:"author"`
	Color      string `json:"color"`
	Head       string `json:"head"`
	Tail       string `json:"tail"`
	Version    string `json:"version"`
}

var GameId string
var Turn int32
var Battlesnakes map[string]Battlesnake
var HttpClient http.Client
var Width int32
var Height int32
var Names []string
var URLs []string
var Squads []string
var Timeout int32
var Sequential bool
var GameType string
var ViewMap bool
var Seed int64
var TurnDelay int32

var FoodSpawnChance int32
var MinimumFood int32
var HazardDamagePerTurn int32
var ShrinkEveryNTurns int32

var playCmd = &cobra.Command{
	Use:   "play",
	Short: "Play a game of Battlesnake locally.",
	Long:  "Play a game of Battlesnake locally.",
	Run:   run,
}

func init() {
	rootCmd.AddCommand(playCmd)

	playCmd.Flags().Int32VarP(&Width, "width", "W", 11, "Width of Board")
	playCmd.Flags().Int32VarP(&Height, "height", "H", 11, "Height of Board")
	playCmd.Flags().StringArrayVarP(&Names, "name", "n", nil, "Name of Snake")
	playCmd.Flags().StringArrayVarP(&URLs, "url", "u", nil, "URL of Snake")
	playCmd.Flags().StringArrayVarP(&Names, "squad", "S", nil, "Squad of Snake")
	playCmd.Flags().Int32VarP(&Timeout, "timeout", "t", 500, "Request Timeout")
	playCmd.Flags().BoolVarP(&Sequential, "sequential", "s", false, "Use Sequential Processing")
	playCmd.Flags().StringVarP(&GameType, "gametype", "g", "standard", "Type of Game Rules")
	playCmd.Flags().BoolVarP(&ViewMap, "viewmap", "v", false, "View the Map Each Turn")
	playCmd.Flags().Int64VarP(&Seed, "seed", "r", time.Now().UTC().UnixNano(), "Random Seed")
	playCmd.Flags().Int32VarP(&TurnDelay, "delay", "d", 0, "Turn Delay in Milliseconds")

	playCmd.Flags().Int32Var(&FoodSpawnChance, "foodSpawnChance", 15, "Percentage chance of spawning a new food every round")
	playCmd.Flags().Int32Var(&MinimumFood, "minimumFood", 1, "Minimum food to keep on the board every turn")
	playCmd.Flags().Int32Var(&HazardDamagePerTurn, "hazardDamagePerTurn", 14, "Health damage a snake will take when ending its turn in a hazard")
	playCmd.Flags().Int32Var(&ShrinkEveryNTurns, "shrinkEveryNTurns", 25, "In Royale mode, the number of turns between generating new hazards")

	playCmd.Flags().SortFlags = false
}

var run = func(cmd *cobra.Command, args []string) {
	rand.Seed(Seed)

	Battlesnakes = make(map[string]Battlesnake)
	GameId = uuid.New().String()
	Turn = 0

	snakes := buildSnakesFromOptions()

	ruleset := getRuleset(Seed, snakes)
	state := initializeBoardFromArgs(ruleset, snakes)
	for _, snake := range snakes {
		Battlesnakes[snake.ID] = snake
	}

	for v := false; !v; v, _ = ruleset.IsGameOver(state) {
		Turn++
		state = createNextBoardState(ruleset, state, snakes, Turn)

		if ViewMap {
			printMap(state, Turn)
		} else {
			log.Printf("[%v]: State: %v\n", Turn, state)
		}

		if TurnDelay > 0 {
			time.Sleep(time.Duration(TurnDelay) * time.Millisecond)
		}
	}

	if GameType == "solo" {
		log.Printf("[DONE]: Game completed after %v turns.", Turn)
	} else {
		var winner string
		isDraw := true
		for _, snake := range state.Snakes {
			if snake.EliminatedCause == rules.NotEliminated {
				isDraw = false
				winner = Battlesnakes[snake.ID].Name
			}
			sendEndRequest(ruleset, state, Battlesnakes[snake.ID])
		}

		if isDraw {
			log.Printf("[DONE]: Game completed after %v turns. It was a draw.", Turn)
		} else {
			log.Printf("[DONE]: Game completed after %v turns. %v is the winner.", Turn, winner)
		}
	}
}

func getRuleset(seed int64, snakes []Battlesnake) rules.Ruleset {
	var ruleset rules.Ruleset
	var royale rules.RoyaleRuleset

	standard := rules.StandardRuleset{
		FoodSpawnChance:     FoodSpawnChance,
		MinimumFood:         MinimumFood,
		HazardDamagePerTurn: 0,
	}

	switch GameType {
	case "royale":
		standard.HazardDamagePerTurn = HazardDamagePerTurn
		royale = rules.RoyaleRuleset{
			StandardRuleset:   standard,
			Seed:              seed,
			ShrinkEveryNTurns: ShrinkEveryNTurns,
		}
		ruleset = &royale
	case "squad":
		squadMap := map[string]string{}
		for _, snake := range snakes {
			squadMap[snake.ID] = snake.Squad
		}
		ruleset = &rules.SquadRuleset{
			StandardRuleset:     standard,
			SquadMap:            squadMap,
			AllowBodyCollisions: true,
			SharedElimination:   true,
			SharedHealth:        true,
			SharedLength:        true,
		}
	case "solo":
		ruleset = &rules.SoloRuleset{
			StandardRuleset: standard,
		}
	case "wrapped":
		ruleset = &rules.WrappedRuleset{
			StandardRuleset: standard,
		}
	case "constrictor":
		ruleset = &rules.ConstrictorRuleset{
			StandardRuleset: standard,
		}
	default:
		ruleset = &standard
	}
	return ruleset
}

func initializeBoardFromArgs(ruleset rules.Ruleset, snakes []Battlesnake) *rules.BoardState {
	if Timeout == 0 {
		Timeout = 500
	}
	HttpClient = http.Client{
		Timeout: time.Duration(Timeout) * time.Millisecond,
	}

	snakeIds := []string{}
	for _, snake := range snakes {
		snakeIds = append(snakeIds, snake.ID)
	}
	state, err := rules.CreateDefaultBoardState(Width, Height, snakeIds)
	if err != nil {
		log.Panic("[PANIC]: Error Initializing Board State")
	}
	state, err = ruleset.ModifyInitialBoardState(state)
	if err != nil {
		log.Panic("[PANIC]: Error Initializing Board State")
	}

	for _, snake := range snakes {
		requestBody := getIndividualBoardStateForSnake(state, snake, ruleset)
		u, _ := url.ParseRequestURI(snake.URL)
		u.Path = path.Join(u.Path, "start")
		_, err = HttpClient.Post(u.String(), "application/json", bytes.NewBuffer(requestBody))
		if err != nil {
			log.Printf("[WARN]: Request to %v failed", u.String())
		}
	}
	return state
}

func createNextBoardState(ruleset rules.Ruleset, state *rules.BoardState, snakes []Battlesnake, turn int32) *rules.BoardState {
	var moves []rules.SnakeMove
	if Sequential {
		for _, snake := range snakes {
			for _, stateSnake := range state.Snakes {
				if snake.ID == stateSnake.ID && stateSnake.EliminatedCause == rules.NotEliminated {
					moves = append(moves, getMoveForSnake(ruleset, state, snake))
				}
			}
		}
	} else {
		var wg sync.WaitGroup
		c := make(chan rules.SnakeMove, len(snakes))

		for _, snake := range snakes {
			for _, stateSnake := range state.Snakes {
				if snake.ID == stateSnake.ID && stateSnake.EliminatedCause == rules.NotEliminated {
					wg.Add(1)
					go getConcurrentMoveForSnake(&wg, ruleset, state, snake, c)
				}
			}
		}

		wg.Wait()
		close(c)

		for move := range c {
			moves = append(moves, move)
		}
	}
	for _, move := range moves {
		snake := Battlesnakes[move.ID]
		snake.LastMove = move.Move
		Battlesnakes[move.ID] = snake
	}
	state, err := ruleset.CreateNextBoardState(state, moves)
	if err != nil {
		log.Panic("[PANIC]: Error Producing Next Board State")
		panic(err)
	}

	state.Turn = turn

	return state
}

func getConcurrentMoveForSnake(wg *sync.WaitGroup, ruleset rules.Ruleset, state *rules.BoardState, snake Battlesnake, c chan rules.SnakeMove) {
	defer wg.Done()
	c <- getMoveForSnake(ruleset, state, snake)
}

func getMoveForSnake(ruleset rules.Ruleset, state *rules.BoardState, snake Battlesnake) rules.SnakeMove {
	requestBody := getIndividualBoardStateForSnake(state, snake, ruleset)
	u, _ := url.ParseRequestURI(snake.URL)
	u.Path = path.Join(u.Path, "move")
	res, err := HttpClient.Post(u.String(), "application/json", bytes.NewBuffer(requestBody))
	move := snake.LastMove
	if err != nil {
		log.Printf("[WARN]: Request to %v failed\n", u.String())
		log.Printf("Body --> %v\n", string(requestBody))
	} else if res.Body != nil {
		defer res.Body.Close()
		body, readErr := ioutil.ReadAll(res.Body)
		if readErr != nil {
			log.Fatal(readErr)
		} else {
			playerResponse := PlayerResponse{}
			jsonErr := json.Unmarshal(body, &playerResponse)
			if jsonErr != nil {
				log.Fatal(jsonErr)
			} else {
				move = playerResponse.Move
			}
		}
	}
	return rules.SnakeMove{ID: snake.ID, Move: move}
}

func sendEndRequest(ruleset rules.Ruleset, state *rules.BoardState, snake Battlesnake) {
	requestBody := getIndividualBoardStateForSnake(state, snake, ruleset)
	u, _ := url.ParseRequestURI(snake.URL)
	u.Path = path.Join(u.Path, "end")
	_, err := HttpClient.Post(u.String(), "application/json", bytes.NewBuffer(requestBody))
	if err != nil {
		log.Printf("[WARN]: Request to %v failed", u.String())
	}
}

func getIndividualBoardStateForSnake(state *rules.BoardState, snake Battlesnake, ruleset rules.Ruleset) []byte {
	var youSnake rules.Snake
	for _, snk := range state.Snakes {
		if snake.ID == snk.ID {
			youSnake = snk
			break
		}
	}
	response := ResponsePayload{
		Game: GameResponse{Id: GameId, Timeout: Timeout, Ruleset: GameResponseRuleset{
			Name:    ruleset.Name(),
			Version: "cli", // TODO: Use GitHub Release Version
		}},
		Turn: Turn,
		Board: BoardResponse{
			Height:  state.Height,
			Width:   state.Width,
			Food:    coordFromPointArray(state.Food),
			Hazards: coordFromPointArray(state.Hazards),
			Snakes:  buildSnakesResponse(state.Snakes),
		},
		You: snakeResponseFromSnake(youSnake),
	}
	responseJson, err := json.Marshal(response)
	if err != nil {
		log.Panic("[PANIC]: Error Marshalling JSON from State")
		panic(err)
	}
	return responseJson
}

func snakeResponseFromSnake(snake rules.Snake) SnakeResponse {
	return SnakeResponse{
		Id:      snake.ID,
		Name:    Battlesnakes[snake.ID].Name,
		Health:  snake.Health,
		Body:    coordFromPointArray(snake.Body),
		Latency: "0",
		Head:    coordFromPoint(snake.Body[0]),
		Length:  int32(len(snake.Body)),
		Shout:   "",
		Squad:   Battlesnakes[snake.ID].Squad,
	}
}

func buildSnakesResponse(snakes []rules.Snake) []SnakeResponse {
	var a []SnakeResponse
	for _, snake := range snakes {
		if snake.EliminatedCause == rules.NotEliminated {
			a = append(a, snakeResponseFromSnake(snake))
		}
	}
	return a
}

func coordFromPoint(pt rules.Point) Coord {
	return Coord{X: pt.X, Y: pt.Y}
}

func coordFromPointArray(ptArray []rules.Point) []Coord {
	a := make([]Coord, 0)
	for _, pt := range ptArray {
		a = append(a, coordFromPoint(pt))
	}
	return a
}

func buildSnakesFromOptions() []Battlesnake {
	bodyChars := []rune{'■', '⌀', '●', '⍟', '◘', '☺', '□', '☻'}
	var numSnakes int
	var snakes []Battlesnake
	numNames := len(Names)
	numURLs := len(URLs)
	numSquads := len(Squads)
	if numNames > numURLs {
		numSnakes = numNames
	} else {
		numSnakes = numURLs
	}
	if numNames != numURLs {
		log.Println("[WARN]: Number of Names and URLs do not match: defaults will be applied to missing values")
	}
	for i := int(0); i < numSnakes; i++ {
		var snakeName string
		var snakeURL string
		var snakeSquad string

		id := uuid.New().String()

		if i < numNames {
			snakeName = Names[i]
		} else {
			log.Printf("[WARN]: Name for URL %v is missing: a default name will be applied\n", URLs[i])
			snakeName = id
		}

		if i < numURLs {
			u, err := url.ParseRequestURI(URLs[i])
			if err != nil {
				log.Printf("[WARN]: URL %v is not valid: a default will be applied\n", URLs[i])
				snakeURL = "https://example.com"
			} else {
				snakeURL = u.String()
			}
		} else {
			log.Printf("[WARN]: URL for Name %v is missing: a default URL will be applied\n", Names[i])
			snakeURL = "https://example.com"
		}

		if GameType == "squad" {
			if i < numSquads {
				snakeSquad = Squads[i]
			} else {
				log.Printf("[WARN]: Squad for URL %v is missing: a default squad will be applied\n", URLs[i])
				snakeSquad = strconv.Itoa(i / 2)
			}
		}
		res, err := HttpClient.Get(snakeURL)
		api := "0"
		if err != nil {
			log.Printf("[WARN]: Request to %v failed", snakeURL)
		} else if res.Body != nil {
			defer res.Body.Close()
			body, readErr := ioutil.ReadAll(res.Body)
			if readErr != nil {
				log.Fatal(readErr)
			}

			pingResponse := PingResponse{}
			jsonErr := json.Unmarshal(body, &pingResponse)
			if jsonErr != nil {
				log.Fatal(jsonErr)
			} else {
				api = pingResponse.APIVersion
			}
		}
		snake := Battlesnake{Name: snakeName, URL: snakeURL, ID: id, API: api, LastMove: "up", Character: bodyChars[i%8]}
		if GameType == "squad" {
			snake.Squad = snakeSquad
		}
		snakes = append(snakes, snake)
	}
	return snakes
}

func printMap(state *rules.BoardState, gameTurn int32) {
	var o bytes.Buffer
	o.WriteString(fmt.Sprintf("Ruleset: %s, Seed: %d, Turn: %v\n", GameType, Seed, gameTurn))
	board := make([][]rune, state.Width)
	for i := range board {
		board[i] = make([]rune, state.Height)
	}
	for y := int32(0); y < state.Height; y++ {
		for x := int32(0); x < state.Width; x++ {
			board[x][y] = '◦'
		}
	}
	for _, oob := range state.Hazards {
		board[oob.X][oob.Y] = '░'
	}
	o.WriteString(fmt.Sprintf("Hazards ░: %v\n", state.Hazards))
	for _, f := range state.Food {
		board[f.X][f.Y] = '⚕'
	}
	o.WriteString(fmt.Sprintf("Food ⚕: %v\n", state.Food))
	for _, s := range state.Snakes {
		for _, b := range s.Body {
			if b.X >= 0 && b.X < state.Width && b.Y >= 0 && b.Y < state.Height {
				board[b.X][b.Y] = Battlesnakes[s.ID].Character
			}
		}
		o.WriteString(fmt.Sprintf("%v %c: %v\n", Battlesnakes[s.ID].Name, Battlesnakes[s.ID].Character, s))
	}
	for y := state.Height - 1; y >= 0; y-- {
		for x := int32(0); x < state.Width; x++ {
			o.WriteRune(board[x][y])
		}
		o.WriteString("\n")
	}
	log.Print(o.String())
}