package image

import (
	"errors"
	"os"

	"github.com/golang/freetype"
	"github.com/golang/freetype/truetype"
	"golang.org/x/image/font/gofont/goregular"

	"douyu_go/internal/logger"
)

// LoadFont 预加载字体，优先使用本地或系统中文字体，缺失时使用内置字体兜底。
func LoadFont(fontFiles []string) *truetype.Font {
	source, font, err := parseFirstFont(fontFiles)
	if err != nil {
		source = "内置 Go Regular 字体"
		font, err = freetype.ParseFont(goregular.TTF)
		if err != nil {
			logger.LogEvent("字体", "error", "内置字体解析失败，成功图片功能将跳过: %v", err)
			return nil
		}
		logger.LogEvent("字体", "warn", "未找到可用系统字体，使用内置字体兜底，中文可能显示不完整")
	}
	logger.LogEvent("字体", "success", "字体加载完成: %s", source)
	return font
}

func parseFirstFont(candidates []string) (string, *truetype.Font, error) {
	for _, path := range candidates {
		if path == "" {
			continue
		}
		fontBytes, err := os.ReadFile(path)
		if err != nil {
			if !errors.Is(err, os.ErrNotExist) {
				logger.LogEvent("字体", "warn", "字体读取失败，已跳过: %s: %v", path, err)
			}
			continue
		}
		if len(fontBytes) == 0 {
			continue
		}
		font, err := freetype.ParseFont(fontBytes)
		if err != nil {
			logger.LogEvent("字体", "warn", "字体解析失败，已跳过: %s: %v", path, err)
			continue
		}
		return path, font, nil
	}
	return "", nil, errors.New("没有可用字体")
}