package httpapi

import (
	"context"
	"crypto/rand"
	"encoding/hex"
	"io"
	"net/http"
	"net/url"
	"os"
	"path/filepath"
	"strings"
	"time"

	"git.yeij.top/AskaEth/Scoreboard/server/internal/auth"
	"git.yeij.top/AskaEth/Scoreboard/server/internal/export"
	"git.yeij.top/AskaEth/Scoreboard/server/internal/rules"
)

const xlsxMIME = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"

// maxProjectImportBytes 是赛事包上传的硬上限，避免超大请求把内存和磁盘撑爆。
const maxProjectImportBytes = 512 << 20

// exportRoutes 挂载 xlsx 导出、赛事项目包与备份查询。
func (s *server) exportRoutes(mux *http.ServeMux) {
	mux.HandleFunc("GET /api/export/standings.xlsx", s.read(auth.RoleGuest, s.exportStandingsXLSX))
	mux.HandleFunc("GET /api/export/all.xlsx", s.read(auth.RoleGuest, s.exportAllXLSX))
	// Go 1.22 ServeMux 的通配段必须独占一段，所以分项/单位导出用 /{id}，文件名由响应头给出。
	mux.HandleFunc("GET /api/export/events/{id}", s.read(auth.RoleGuest, s.exportEventXLSX))
	mux.HandleFunc("GET /api/export/teams/{id}", s.read(auth.RoleGuest, s.exportTeamXLSX))

	mux.HandleFunc("GET /api/export/project.zip", s.read(auth.RoleAdmin, s.exportProjectZip))
	mux.HandleFunc("POST /api/export/project/import", s.write(auth.RoleAdmin, s.importProjectZip))
	mux.HandleFunc("GET /api/export/backups", s.read(auth.RoleAdmin, s.listBackups))
}

// streamDownload 直接写响应体；返回 errHandled 让统一响应层不再追加 JSON。
func (s *server) streamDownload(w http.ResponseWriter, filename, contentType string, write func(io.Writer) error) (any, error) {
	w.Header().Set("Content-Type", contentType)
	w.Header().Set("Content-Disposition", "attachment; filename*=UTF-8''"+url.PathEscape(filename))
	if err := write(w); err != nil {
		s.logger.Error("导出写出失败", "file", filename, "err", err)
	}
	return nil, errHandled
}

func (s *server) exportStandingsXLSX(w http.ResponseWriter, r *http.Request) (any, error) {
	wb, err := export.LoadStandingsWorkbook(s.ev, export.Options{})
	if err != nil {
		return nil, internal(err)
	}
	return s.streamDownload(w, "总积分榜.xlsx", xlsxMIME, func(out io.Writer) error {
		return export.WriteStandingsXLSX(out, wb)
	})
}

func (s *server) exportEventXLSX(w http.ResponseWriter, r *http.Request) (any, error) {
	id, err := pathID(r, "id")
	if err != nil {
		return nil, err
	}
	wb, err := export.LoadEventWorkbook(s.ev, id, export.Options{})
	if err != nil {
		return nil, internal(err)
	}
	return s.streamDownload(w, "分项成绩表.xlsx", xlsxMIME, func(out io.Writer) error {
		return export.WriteEventXLSX(out, wb)
	})
}

func (s *server) exportAllXLSX(w http.ResponseWriter, r *http.Request) (any, error) {
	wb, err := export.LoadAllWorkbook(s.ev, export.Options{})
	if err != nil {
		return nil, internal(err)
	}
	return s.streamDownload(w, "赛事成绩总表.xlsx", xlsxMIME, func(out io.Writer) error {
		return export.WriteAllXLSX(out, wb)
	})
}

func (s *server) exportTeamXLSX(w http.ResponseWriter, r *http.Request) (any, error) {
	id, err := pathID(r, "id")
	if err != nil {
		return nil, err
	}
	wb, err := export.LoadTeamDetailWorkbook(s.ev, id, export.Options{})
	if err != nil {
		return nil, internal(err)
	}
	return s.streamDownload(w, "单位积分明细.xlsx", xlsxMIME, func(out io.Writer) error {
		return export.WriteTeamDetailXLSX(out, wb)
	})
}

func (s *server) exportProjectZip(w http.ResponseWriter, r *http.Request) (any, error) {
	dir := filepath.Join(s.dataDir, "exports")
	if err := os.MkdirAll(dir, 0o755); err != nil {
		return nil, internal(err)
	}
	// 项目名取赛事设置里的 event.name；为空会触发 SafeProjectName 校验失败，回退到固定名
	name := "scoreboard-project"
	var raw string
	if err := s.ev.QueryRowContext(r.Context(),
		`SELECT value FROM settings WHERE key = 'event.name'`).Scan(&raw); err == nil && raw != "" {
		name = raw
	}

	opts := export.ProjectExportOptions{Name: name, AppVersion: s.version}
	if s.projectDir != "" {
		// uploads 可能还没建过；只在目录存在时打包，否则 copyTree 会报错。
		uploads := filepath.Join(s.projectDir, "uploads")
		if info, err := os.Stat(uploads); err == nil && info.IsDir() {
			opts.UploadsDir = uploads
		}
	}
	rulesPath, cleanup, err := s.writeRulesTempFile(r.Context())
	if err != nil {
		return nil, err
	}
	defer cleanup()
	opts.RulesPath = rulesPath

	dst, err := projectExportPath(dir, time.Now())
	if err != nil {
		return nil, internal(err)
	}
	if _, err := export.ExportProjectZip(s.ev, dst, opts); err != nil {
		return nil, internal(err)
	}
	defer func() { _ = os.Remove(dst) }()

	w.Header().Set("Content-Type", "application/zip")
	w.Header().Set("Content-Disposition", "attachment; filename*=UTF-8''"+url.PathEscape("赛事项目包.zip"))
	http.ServeFile(w, r, dst)
	return nil, errHandled
}

// projectExportPath 生成带随机后缀的导出文件名：精度到秒的时间戳在并发导出时会撞名，
// 后写的会截断先写的文件，导致先返回的响应内容损坏。
func projectExportPath(dir string, now time.Time) (string, error) {
	suffix := make([]byte, 4)
	if _, err := rand.Read(suffix); err != nil {
		return "", err
	}
	return filepath.Join(dir, "project-"+now.Format("20060102-150405")+"-"+hex.EncodeToString(suffix)+".zip"), nil
}

// writeRulesTempFile 把当前规则包导出成临时 YAML，供赛事项目包内嵌 rules.yaml。
// 返回的清理函数由调用方 defer，避免临时文件泄漏。
func (s *server) writeRulesTempFile(ctx context.Context) (string, func(), error) {
	pack, err := rules.Export(s.ev, rules.Meta{})
	if err != nil {
		return "", func() {}, internal(err)
	}
	body, err := rules.Marshal(pack)
	if err != nil {
		return "", func() {}, internal(err)
	}
	f, err := os.CreateTemp("", "scoreboard-rules-*.yaml")
	if err != nil {
		return "", func() {}, internal(err)
	}
	if _, err := f.Write(body); err != nil {
		_ = f.Close()
		_ = os.Remove(f.Name())
		return "", func() {}, internal(err)
	}
	if err := f.Close(); err != nil {
		_ = os.Remove(f.Name())
		return "", func() {}, internal(err)
	}
	return f.Name(), func() { _ = os.Remove(f.Name()) }, nil
}

func (s *server) importProjectZip(w http.ResponseWriter, r *http.Request) (any, error) {
	r.Body = http.MaxBytesReader(w, r.Body, maxProjectImportBytes)
	if err := r.ParseMultipartForm(512 << 20); err != nil {
		return nil, badRequest("解析上传失败", nil)
	}
	file, _, err := r.FormFile("file")
	if err != nil {
		return nil, badRequest("缺少上传字段 file", nil)
	}
	defer func() { _ = file.Close() }()

	tmpDir, err := os.MkdirTemp("", "scoreboard-import-")
	if err != nil {
		return nil, internal(err)
	}
	defer func() { _ = os.RemoveAll(tmpDir) }()

	tmp := filepath.Join(tmpDir, "project.zip")
	out, err := os.Create(tmp)
	if err != nil {
		return nil, internal(err)
	}
	if _, err := io.Copy(out, file); err != nil {
		_ = out.Close()
		return nil, internal(err)
	}
	if err := out.Close(); err != nil {
		return nil, internal(err)
	}

	// 覆盖正在运行的赛事项目会让运行中的 event.db 被 unlink（Linux）或 rename 失败（Windows），
	// 现场继续写进已删除的 inode，重启即丢数据，必须在落盘前直接拒绝。
	if cur := currentProjectName(s.projectDir); cur != "" {
		meta, err := export.InspectProjectZip(tmp)
		if err != nil {
			return nil, badRequest(err.Error(), nil)
		}
		name := meta.Name
		if v := strings.TrimSpace(r.FormValue("rename")); v != "" {
			name = v
		}
		if safe, err := export.SafeProjectName(name); err == nil && strings.EqualFold(safe, cur) {
			return nil, badRequest("不能覆盖正在运行的赛事项目 "+cur, nil)
		}
	}

	res, err := export.ImportProjectZip(tmp, filepath.Join(s.dataDir, "event_projs"), export.ImportOptions{
		Overwrite: r.FormValue("overwrite") == "1",
		Rename:    r.FormValue("rename"),
	})
	if err != nil {
		return nil, badRequest(err.Error(), nil)
	}
	s.audit(r.Context(), "project.import", "project", 0, nil, res)
	return res, nil
}

// currentProjectName 从项目目录反推当前运行的赛事项目名；未配置目录时返回空串。
func currentProjectName(projectDir string) string {
	cleaned := filepath.Clean(strings.TrimSpace(projectDir))
	if cleaned == "" || cleaned == "." || cleaned == string(filepath.Separator) {
		return ""
	}
	return filepath.Base(cleaned)
}

func (s *server) listBackups(w http.ResponseWriter, r *http.Request) (any, error) {
	items, err := export.ListBackups(filepath.Join(s.dataDir, "backups"), "")
	if err != nil {
		return nil, internal(err)
	}
	return items, nil
}