package handler

import (
	"log"
	"net/http"
	"os"
	"path/filepath"
	"runtime"

	"github.com/gin-gonic/gin"
	"gopkg.in/yaml.v3"
)

type versionConfig struct {
	Version      string            `yaml:"version"`
	BuildNumber  int               `yaml:"build_number"`
	ForceUpdate  bool              `yaml:"force_update"`
	ReleaseNotes string            `yaml:"release_notes"`
	DownloadURLs map[string]string `yaml:"download_urls"`
	// Changelog 由 client 发版脚本从 CHANGELOG-client.md 写入（最近 3 条），
	// 供官网下载页运行时拉取渲染更新日志，无需重建官网。
	Changelog []changelogEntry `yaml:"changelog"`
}

type changelogEntry struct {
	Version  string             `yaml:"version" json:"version"`
	Date     string             `yaml:"date" json:"date"`
	Intro    string             `yaml:"intro" json:"intro"`
	Sections []changelogSection `yaml:"sections" json:"sections"`
}

type changelogSection struct {
	Type  string   `yaml:"type" json:"type"`
	Items []string `yaml:"items" json:"items"`
}

// changelogOrEmpty 保证响应里 changelog 始终是数组（而非 null），方便前端遍历。
func changelogOrEmpty(c []changelogEntry) []changelogEntry {
	if c == nil {
		return []changelogEntry{}
	}
	return c
}

// GetVersion GET /version
func GetVersion(c *gin.Context) {
	cfg, err := loadVersionConfig()
	if err != nil {
		log.Printf("[version] failed to load version config: %v", err)
		c.JSON(http.StatusInternalServerError, gin.H{"error": "version config unavailable"})
		return
	}
	c.JSON(http.StatusOK, gin.H{
		"version":       cfg.Version,
		"build_number":  cfg.BuildNumber,
		"force_update":  cfg.ForceUpdate,
		"release_notes": cfg.ReleaseNotes,
		"download_urls": cfg.DownloadURLs,
		"changelog":     changelogOrEmpty(cfg.Changelog),
	})
}

func loadVersionConfig() (*versionConfig, error) {
	// 查找 config/version.yaml，相对于可执行文件或源码目录
	candidates := []string{
		"config/version.yaml",
		filepath.Join(sourceDir(), "config/version.yaml"),
	}
	for _, path := range candidates {
		data, err := os.ReadFile(path)
		if err != nil {
			continue
		}
		var cfg versionConfig
		if err := yaml.Unmarshal(data, &cfg); err != nil {
			return nil, err
		}
		return &cfg, nil
	}
	return nil, os.ErrNotExist
}

// sourceDir 返回当前源文件所在目录的上两级（backend 根目录）
func sourceDir() string {
	_, filename, _, ok := runtime.Caller(0)
	if !ok {
		return "."
	}
	// handler/ → internal/ → backend/
	return filepath.Join(filepath.Dir(filename), "..", "..")
}