package game

import (
	"fmt"
	"strconv"
	"strings"

	"thehouseoficarus/internal/net"
	"thehouseoficarus/internal/player"
	"thehouseoficarus/internal/world"
)

func (g *Game) executeWalk(sess *net.Session, args []string, rawInput string) {
	g.doWalk(sess, args)
}

func (g *Game) doWalk(sess *net.Session, args []string) {
	p := sess.Player
	if len(args) == 0 {
		sess.WriteLine("Walk where?")
		return
	}

	input := strings.Join(args, "")
	if roomID, err := strconv.Atoi(input); err == nil {
		path := g.findPathToRoom(p.RoomID, roomID)
		if path == nil {
			sess.WriteLine(fmt.Sprintf("No path found to room #%d.", roomID))
			return
		}
		g.startWalk(sess, p, path)
		return
	}

	dirs, err := parseWalkDirections(input)
	if err != nil {
		sess.WriteLine(err.Error())
		return
	}
	g.startWalk(sess, p, dirs)
}

func parseWalkDirections(input string) ([]string, error) {
	var dirs []string
	i := 0
	for i < len(input) {
		num := 0
		for i < len(input) && input[i] >= '0' && input[i] <= '9' {
			num = num*10 + int(input[i]-'0')
			i++
		}
		if num == 0 {
			num = 1
		}
		if i >= len(input) {
			return nil, fmt.Errorf("Unexpected end of directions.")
		}
		ch := input[i]
		i++
		var dir string
		switch ch {
		case 'n':
			dir = string(world.North)
		case 's':
			dir = string(world.South)
		case 'e':
			dir = string(world.East)
		case 'w':
			dir = string(world.West)
		case 'u':
			dir = string(world.Up)
		case 'd':
			dir = string(world.Down)
		default:
			return nil, fmt.Errorf("Unknown direction: %c", ch)
		}
		for j := 0; j < num; j++ {
			dirs = append(dirs, dir)
		}
	}
	return dirs, nil
}

func (g *Game) startWalk(sess *net.Session, p *player.Player, dirs []string) {
	agilityLevel := p.Level(player.Agility)
	if agilityLevel < 1 {
		agilityLevel = 1
	}
	if len(dirs) > agilityLevel {
		sess.WriteLine(fmt.Sprintf("You can only make %d moves at once with your current agility level!", agilityLevel))
		return
	}

	g.cancelAction(p)
	p.WalkSequence = dirs
}

func (g *Game) advanceWalk(sess *net.Session, p *player.Player) {
	if p.MoveTicks > 0 {
		return
	}
	if len(p.WalkSequence) == 0 {
		return
	}

	dir := p.WalkSequence[0]
	remaining := condensePath(p.WalkSequence[1:])
	p.WalkSequence = p.WalkSequence[1:]

	oldRoom := p.RoomID
	g.doMove(sess, dir, 2.0)

	if p.MoveTicks == 0 && p.RoomID == oldRoom {
		p.WalkSequence = nil
		return
	}

	if len(p.WalkSequence) > 0 && remaining != "" {
		sess.WriteLine(fmt.Sprintf("You're headed: %s.", remaining))
	}
}

func condensePath(dirs []string) string {
	if len(dirs) == 0 {
		return ""
	}
	var result strings.Builder
	i := 0
	for i < len(dirs) {
		count := 1
		for i+count < len(dirs) && dirs[i+count] == dirs[i] {
			count++
		}
		if count > 1 {
			result.WriteString(fmt.Sprintf("%d", count))
		}
		result.WriteString(directionToChar(dirs[i]))
		i += count
	}
	return result.String()
}

func directionToChar(dir string) string {
	switch world.ExitDir(dir) {
	case world.North:
		return "n"
	case world.South:
		return "s"
	case world.East:
		return "e"
	case world.West:
		return "w"
	case world.Up:
		return "u"
	case world.Down:
		return "d"
	}
	return "?"
}

var bfsSearchDirs = []world.ExitDir{world.North, world.South, world.East, world.West, world.Up, world.Down}

func (g *Game) findPathToRoom(fromRoom, toRoom int) []string {
	if fromRoom == toRoom {
		return nil
	}

	type bfsNode struct {
		roomID int
		path   []string
	}

	visited := make(map[int]bool)
	queue := []bfsNode{{fromRoom, nil}}
	visited[fromRoom] = true

	for len(queue) > 0 {
		cur := queue[0]
		queue = queue[1:]

		room, ok := loadRoom(g, cur.roomID)
		if !ok {
			continue
		}

		for _, dir := range bfsSearchDirs {
			exitDef, exists := room.Exits[dir]
			if !exists {
				continue
			}
			if visited[exitDef.Room] {
				continue
			}

			newPath := make([]string, len(cur.path)+1)
			copy(newPath, cur.path)
			newPath[len(cur.path)] = string(dir)

			if exitDef.Room == toRoom {
				return newPath
			}

			visited[exitDef.Room] = true
			queue = append(queue, bfsNode{exitDef.Room, newPath})
		}
	}

	return nil
}