package ui

import (
	"fmt"

	"github.com/ryanhamamura/c4/snake"
	"github.com/ryanhamamura/via/h"
)

func SnakeBoard(sg *snake.SnakeGame) h.H {
	state := sg.State
	if state == nil || sg.Status != snake.StatusInProgress && sg.Status != snake.StatusFinished {
		return nil
	}

	// Build a lookup grid for rendering
	type cellInfo struct {
		snakeIdx int // -1 = empty, -2 = food
		isHead   bool
	}
	grid := make([][]cellInfo, state.Height)
	for y := 0; y < state.Height; y++ {
		grid[y] = make([]cellInfo, state.Width)
		for x := 0; x < state.Width; x++ {
			grid[y][x] = cellInfo{snakeIdx: -1}
		}
	}

	for fi := range state.Food {
		f := state.Food[fi]
		if f.X >= 0 && f.X < state.Width && f.Y >= 0 && f.Y < state.Height {
			grid[f.Y][f.X] = cellInfo{snakeIdx: -2}
		}
	}

	for si, s := range state.Snakes {
		if s == nil {
			continue
		}
		for bi, bp := range s.Body {
			if bp.X >= 0 && bp.X < state.Width && bp.Y >= 0 && bp.Y < state.Height {
				grid[bp.Y][bp.X] = cellInfo{snakeIdx: si, isHead: bi == 0}
			}
		}
	}

	// Cell size scales with grid dimensions
	cellSize := cellSizeForGrid(state.Width, state.Height)

	var rows []h.H
	for y := 0; y < state.Height; y++ {
		var cells []h.H
		for x := 0; x < state.Width; x++ {
			ci := grid[y][x]
			class := "snake-cell"
			style := fmt.Sprintf("width:%dpx;height:%dpx;", cellSize, cellSize)

			switch {
			case ci.snakeIdx == -2:
				class += " snake-food"
			case ci.snakeIdx >= 0:
				s := state.Snakes[ci.snakeIdx]
				colorIdx := ci.snakeIdx
				bg := ""
				if colorIdx < len(snake.SnakeColors) {
					bg = snake.SnakeColors[colorIdx]
					style += fmt.Sprintf("background:%s;", bg)
				}
				if !s.Alive {
					class += " snake-dead"
				}
				if ci.isHead {
					class += " snake-head"
					if bg != "" {
						style += fmt.Sprintf("box-shadow:0 0 8px %s;", bg)
					}
				}
			}

			cells = append(cells, h.Div(h.Class(class), h.Attr("style", style)))
		}
		rowAttrs := append([]h.H{h.Class("snake-row")}, cells...)
		rows = append(rows, h.Div(rowAttrs...))
	}

	boardStyle := fmt.Sprintf("grid-template-columns:repeat(%d,1fr);", state.Width)
	attrs := []h.H{
		h.Class("snake-board"),
		h.Attr("style", boardStyle),
	}
	attrs = append(attrs, rows...)
	return h.Div(attrs...)
}

func cellSizeForGrid(width, height int) int {
	maxDim := width
	if height > maxDim {
		maxDim = height
	}
	switch {
	case maxDim <= 15:
		return 28
	case maxDim <= 20:
		return 24
	case maxDim <= 30:
		return 20
	case maxDim <= 40:
		return 16
	default:
		return 14
	}
}