package agent

import (
	"context"
	"errors"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"

	"github.com/gogf/gf/v2/frame/g"
)

const (
	renderFramesCount = 36
	renderFrameSize   = "256x512"
	renderTimeout     = 15 * time.Minute
)

// RenderAvatarFrames 将化身 GLB 预渲染为绕 Y 轴旋转帧序列，返回帧目录访问 URL。
// 帧目录已就绪直接复用；render.enabled=false 或渲染失败时返回 error，由调用方降级。
func RenderAvatarFrames(ctx context.Context, glb string, outKey string) (framesURL string, err error) {
	if !g.Cfg().MustGet(ctx, "render.enabled", true).Bool() {
		return "", errors.New("3D 渲染服务未启用")
	}
	dir := filepath.Join("workspace", "avatar_frames", outKey)
	if framesReady(dir) {
		return "/workspace/avatar_frames/" + outKey, nil
	}
	if _, err := os.Stat(glb); err != nil {
		return "", fmt.Errorf("化身 GLB 不存在: %w", err)
	}
	if err := runRender(ctx, glb, dir); err != nil {
		return "", err
	}
	return "/workspace/avatar_frames/" + outKey, nil
}

func framesReady(dir string) bool {
	entries, err := os.ReadDir(dir)
	if err != nil {
		return false
	}
	count := 0
	for _, e := range entries {
		if strings.HasPrefix(e.Name(), "frame_") && strings.HasSuffix(e.Name(), ".png") {
			count++
		}
	}
	return count >= renderFramesCount
}

func nodeBin(ctx context.Context) string {
	bin := g.Cfg().MustGet(ctx, "render.node_bin", "node").String()
	if bin == "" {
		return "node"
	}
	// 配置路径不存在（如容器环境）→ 回退 PATH 中的 node
	if _, err := os.Stat(bin); err != nil {
		return "node"
	}
	return bin
}

func runRender(ctx context.Context, glb, out string) error {
	if err := os.MkdirAll(out, 0o755); err != nil {
		return err
	}
	return execNode(ctx, filepath.Join("scripts", "avatar-render", "render.js"),
		"--glb", glb, "--out", out,
		"--frames", fmt.Sprint(renderFramesCount), "--size", renderFrameSize)
}

func execNode(ctx context.Context, script string, args ...string) error {
	cmdCtx, cancel := context.WithTimeout(ctx, renderTimeout)
	defer cancel()
	cmd := exec.CommandContext(cmdCtx, nodeBin(ctx), append([]string{script}, args...)...)
	out, err := cmd.CombinedOutput()
	if err != nil {
		return fmt.Errorf("node 渲染失败: %v: %s", err, strings.TrimSpace(string(out)))
	}
	return nil
}