// 仅读取 build 后的报告 JSON，本地渲染 qiye.html（不执行 BuildReportFromRawSources）。
//
//	go run ./cmd/qygl_report_preview -in resources/dev-report/built.json
//	go run ./cmd/qygl_report_preview -in built.json -addr :8899 -watch
//
// 每次打开/刷新页面都会重新读取 -in 文件；加 -watch 后保存 JSON 会自动刷新浏览器。
package main

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"html/template"
	"log"
	"net/http"
	"os"
	"path/filepath"
)

func parseBuiltReport(data []byte) (map[string]interface{}, error) {
	var root map[string]interface{}
	if err := json.Unmarshal(data, &root); err != nil {
		return nil, err
	}
	if _, ok := root["jiguangFull"]; ok {
		return nil, fmt.Errorf("检测到 raw 字段 jiguangFull，请先执行: go run ./cmd/qygl_report_build -in <raw.json> -out built.json")
	}
	if k, _ := root["kind"].(string); k == "full" {
		r, ok := root["report"].(map[string]interface{})
		if !ok {
			return nil, fmt.Errorf("kind=full 时缺少 report 对象")
		}
		return r, nil
	}
	if r, ok := root["report"].(map[string]interface{}); ok {
		return r, nil
	}
	if root["entName"] != nil || root["basic"] != nil || root["reportTime"] != nil {
		return root, nil
	}
	return nil, fmt.Errorf("不是有效的 build 后报告（根级应有 entName、basic、reportTime 之一，或 {\"report\":{...}} / kind=full）")
}

func fileVersionTag(path string) (string, error) {
	st, err := os.Stat(path)
	if err != nil {
		return "", err
	}
	return fmt.Sprintf("%d-%d", st.ModTime().UnixNano(), st.Size()), nil
}

func renderPage(tmpl *template.Template, report map[string]interface{}, injectLive bool) ([]byte, error) {
	reportBytes, err := json.Marshal(report)
	if err != nil {
		return nil, err
	}
	var buf bytes.Buffer
	if err := tmpl.Execute(&buf, map[string]interface{}{
		"ReportJSON": template.JS(reportBytes),
	}); err != nil {
		return nil, err
	}
	b := buf.Bytes()
	if !injectLive {
		return b, nil
	}
	script := `<script>(function(){var v0=null;function tick(){fetch("/__version?="+Date.now(),{cache:"no-store"}).then(function(r){return r.text();}).then(function(v){if(v==="")return;if(v0===null)v0=v;else if(v0!==v){v0=v;location.reload();}}).catch(function(){});}setInterval(tick,600);tick();})();</script>`
	closing := []byte("</body>")
	idx := bytes.LastIndex(b, closing)
	if idx < 0 {
		return append(b, []byte(script)...), nil
	}
	out := make([]byte, 0, len(b)+len(script))
	out = append(out, b[:idx]...)
	out = append(out, script...)
	out = append(out, b[idx:]...)
	return out, nil
}

func main() {
	addr := flag.String("addr", ":8899", "监听地址")
	root := flag.String("root", ".", "项目根目录（含 resources/qiye.html）")
	inPath := flag.String("in", "", "build 后的 JSON（由 qygl_report_build 生成，或 fixture.full 中的 report 形态）")
	watch := flag.Bool("watch", false, "监听 -in 文件变化并自动刷新浏览器（轮询）")
	flag.Parse()

	if *inPath == "" {
		log.Fatal("请指定 -in <built.json>")
	}

	rootAbs, err := filepath.Abs(*root)
	if err != nil {
		log.Fatalf("解析 root: %v", err)
	}
	tplPath := filepath.Join(rootAbs, "resources", "qiye.html")
	if _, err := os.Stat(tplPath); err != nil {
		log.Fatalf("未找到模板 %s: %v", tplPath, err)
	}

	var inAbs string
	if filepath.IsAbs(*inPath) {
		inAbs = *inPath
	} else {
		inAbs = filepath.Join(rootAbs, *inPath)
	}

	if _, err := os.Stat(inAbs); err != nil {
		log.Fatalf("读取 %s: %v", inAbs, err)
	}

	tmpl, err := template.ParseFiles(tplPath)
	if err != nil {
		log.Fatalf("解析模板: %v", err)
	}

	http.HandleFunc("/__version", func(w http.ResponseWriter, r *http.Request) {
		tag, err := fileVersionTag(inAbs)
		if err != nil {
			http.Error(w, err.Error(), http.StatusNotFound)
			return
		}
		w.Header().Set("Cache-Control", "no-store")
		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
		_, _ = w.Write([]byte(tag))
	})

	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path != "/" {
			http.NotFound(w, r)
			return
		}
		raw, err := os.ReadFile(inAbs)
		if err != nil {
			http.Error(w, "读取报告文件失败: "+err.Error(), http.StatusInternalServerError)
			return
		}
		report, err := parseBuiltReport(raw)
		if err != nil {
			http.Error(w, "解析 JSON 失败: "+err.Error(), http.StatusInternalServerError)
			return
		}
		html, err := renderPage(tmpl, report, *watch)
		if err != nil {
			http.Error(w, "渲染失败: "+err.Error(), http.StatusInternalServerError)
			return
		}
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		_, _ = w.Write(html)
	})

	log.Printf("报告预览: http://127.0.0.1%s/  （每请求重读 %s）", *addr, inAbs)
	if *watch {
		log.Printf("已启用 -watch：保存 JSON 后约 0.6s 内自动刷新页面")
	}
	if err := http.ListenAndServe(*addr, nil); err != nil {
		log.Fatal(err)
	}
}