// backend/main.go
package main

import (
	"embed"
	"encoding/json"
	"fmt"
	"io/fs"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"time"

	"github.com/go-chi/chi/v5"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"github.com/tus/tusd/pkg/filestore"
	tusd "github.com/tus/tusd/pkg/handler"
	"github.com/tus/tusd/pkg/memorylocker"

	"scm.bstein.dev/bstein/Pegasus/backend/internal"
)

//go:embed web/dist
var webFS embed.FS

var (
	mediaRoot   = env("PEGASUS_MEDIA_ROOT", "/media")
	userMapFile = env("PEGASUS_USER_MAP_FILE", "/config/user-map.yaml")
	tusDir      = env("PEGASUS_TUS_DIR", filepath.Join(mediaRoot, ".pegasus-tus"))
	jf          = internal.NewJellyfin()
)

var (
    version = "dev"   // set via -ldflags "-X main.version=1.2.0 -X main.git=$(git rev-parse --short HEAD) -X main.builtAt=$(date -u +%Y-%m-%dT%H:%M:%SZ)"
    git     = ""
    builtAt = ""
)

type loggingRW struct {
	http.ResponseWriter
	status int
}

func (l *loggingRW) WriteHeader(code int) { l.status = code; l.ResponseWriter.WriteHeader(code) }

func main() {
	internal.Logf("PEGASUS_DEBUG=%v, DRY_RUN=%v, TUS_DIR=%s, MEDIA_ROOT=%s", internal.Debug, internal.DryRun, tusDir, mediaRoot)

	if os.Getenv("PEGASUS_SESSION_KEY") == "" {
					log.Fatal("PEGASUS_SESSION_KEY is not set")
	}

	um, err := internal.LoadUserMap(userMapFile)
	must(err, "load user map")

	// === tusd setup (resumable uploads) ===
	store := filestore.FileStore{Path: tusDir}
	// ensure upload scratch dir exists
	if err := os.MkdirAll(tusDir, 0o755); err != nil {
					log.Fatalf("mkdir %s: %v", tusDir, err)
	}
	locker := memorylocker.New()
	composer := tusd.NewStoreComposer()
	store.UseIn(composer)
	locker.UseIn(composer)

	// completeC := make(chan tusd.HookEvent)
	config := tusd.Config{
		BasePath:              "/tus/",
		StoreComposer:         composer,
		NotifyCompleteUploads: true,
		// CompleteUploads:       completeC,
		MaxSize:               4 * 1024 * 1024 * 1024, // 4GB per file
	}
	tusHandler, err := tusd.NewUnroutedHandler(config)
	must(err, "init tus handler")
	completeC := tusHandler.CompleteUploads		

	// ---- post-finish hook: enforce naming & mapping ----
	go func() {
		for ev := range completeC {
			claims, err := claimsFromHook(ev)
			if err != nil {
				internal.Logf("tus: no session: %v", err)
				continue
			}

			// read metadata set by the UI
			meta := ev.Upload.MetaData
			desc := strings.TrimSpace(meta["desc"])
			if desc == "" {
				internal.Logf("tus: missing desc; rejecting")
				continue
			}
			date := strings.TrimSpace(meta["date"]) // YYYY-MM-DD or empty
			subdir := strings.Trim(strings.TrimSpace(meta["subdir"]), "/")
			orig := meta["filename"]
			if orig == "" {
				orig = "upload.bin"
			}

			// resolve per-user root
			userRootRel, err := um.Resolve(claims.Username)
			if err != nil {
				internal.Logf("tus: user map missing: %v", err)
				continue
			}

			// compose final name & target
			finalName, err := internal.ComposeFinalName(date, desc, orig)
			if err != nil {
				internal.Logf("tus: bad target name: %v", err)
				continue
			}

			rootAbs, _ := internal.SafeJoin(mediaRoot, userRootRel)
			var targetAbs string
			if subdir == "" {
				targetAbs, err = internal.SafeJoin(rootAbs, finalName)
			} else {
				targetAbs, err = internal.SafeJoin(rootAbs, filepath.Join(subdir, finalName))
			}
			if err != nil {
				internal.Logf("tus: path escape prevented: %v", err)
				continue
			}

			srcPath := ev.Upload.Storage["Path"]
			_ = os.MkdirAll(filepath.Dir(targetAbs), 0o755)
			if internal.DryRun {
				internal.Logf("[DRY] move %s -> %s", srcPath, targetAbs)
			} else if err := os.Rename(srcPath, targetAbs); err != nil {
				internal.Logf("move failed: %v", err)
				continue
			}
			internal.Logf("uploaded: %s", targetAbs)

			// kick Jellyfin refresh
			jf.RefreshLibrary(claims.JFToken)
		}
	}()

	// === chi router ===
	r := chi.NewRouter()
	r.Use(corsForTus)

	// health/version
	r.Get("/healthz", func(w http.ResponseWriter, _ *http.Request) {
					w.WriteHeader(http.StatusOK)
					_, _ = w.Write([]byte("ok"))
	})
	r.Get("/version", func(w http.ResponseWriter, _ *http.Request) {
					_ = json.NewEncoder(w).Encode(map[string]any{
									"version":  version,
									"git":      git,
									"built_at": builtAt,
					})
	})

	// auth
	r.Post("/api/login", func(w http.ResponseWriter, r *http.Request) {
		var f struct {
			Username string `json:"username"`
			Password string `json:"password"`
		}
		if err := json.NewDecoder(r.Body).Decode(&f); err != nil {
			http.Error(w, "bad json", http.StatusBadRequest)
			return
		}
		res, err := jf.AuthenticateByName(f.Username, f.Password)
		if err != nil {
			http.Error(w, "invalid credentials", http.StatusUnauthorized)
			return
		}
		if err := internal.SetSession(w, res.User.Username, res.AccessToken); err != nil {
			http.Error(w, "session error", http.StatusInternalServerError)
			return
		}
		_ = json.NewEncoder(w).Encode(map[string]any{"ok": true})
	})
	r.Post("/api/logout", func(w http.ResponseWriter, _ *http.Request) {
		internal.ClearSession(w)
		_ = json.NewEncoder(w).Encode(map[string]any{"ok": true})
	})

	// whoami
	r.Get("/api/whoami", func(w http.ResponseWriter, r *http.Request) {
		cl, err := internal.CurrentUser(r)
		if err != nil {
			http.Error(w, "unauthorized", http.StatusUnauthorized)
			return
		}
		dr, err := um.Resolve(cl.Username)
		if err != nil {
			http.Error(w, "no mapping", http.StatusForbidden)
			return
		}
		_ = json.NewEncoder(w).Encode(map[string]any{"username": cl.Username, "root": dr})
	})

	// list entries
	r.Get("/api/list", func(w http.ResponseWriter, r *http.Request) {
		cl, err := internal.CurrentUser(r)
		if err != nil {
			http.Error(w, "unauthorized", http.StatusUnauthorized)
			return
		}
		rootRel, err := um.Resolve(cl.Username)
		if err != nil {
			http.Error(w, "forbidden", http.StatusForbidden)
			return
		}
		q := strings.TrimPrefix(r.URL.Query().Get("path"), "/")
		rootAbs, _ := internal.SafeJoin(mediaRoot, rootRel)
		var dirAbs string
		if q == "" {
			dirAbs = rootAbs
		} else {
			dirAbs, err = internal.SafeJoin(rootAbs, q)
			if err != nil {
				http.Error(w, "forbidden", http.StatusForbidden)
				return
			}
		}
		ents, err := os.ReadDir(dirAbs)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		type entry struct {
			Name  string
			Path  string
			IsDir bool
			Size  int64
			Mtime int64
		}
		var out []entry
		for _, d := range ents {
			info, _ := d.Info()
			out = append(out, entry{
				Name:  d.Name(),
				Path:  filepath.Join(q, d.Name()),
				IsDir: d.IsDir(),
				Size: func() int64 {
					if info != nil && !d.IsDir() {
						return info.Size()
					}
					return 0
				}(),
				Mtime: func() int64 {
					if info != nil {
						return info.ModTime().Unix()
					}
					return 0
				}(),
			})
		}
		_ = json.NewEncoder(w).Encode(out)
	})

	// rename
	var finalNameRe = regexp.MustCompile(`^\d{4}\.\d{2}\.\d{2}\.[A-Za-z0-9_-]{1,64}\.[A-Za-z0-9]{1,8}$`)
	r.Post("/api/rename", func(w http.ResponseWriter, r *http.Request) {
		cl, err := internal.CurrentUser(r)
		if err != nil {
			http.Error(w, "unauthorized", http.StatusUnauthorized)
			return
		}
		var p struct {
			From string `json:"from"`
			To   string `json:"to"`
		}
		if err := json.NewDecoder(r.Body).Decode(&p); err != nil {
			http.Error(w, "bad json", http.StatusBadRequest)
			return
		}

		// enforce final name on files (allow any name for directories)
		if filepath.Ext(p.To) != "" && !finalNameRe.MatchString(filepath.Base(p.To)) {
			http.Error(w, "new name must match YYYY.MM.DD.Description.ext", http.StatusBadRequest)
			return
		}

		rootRel, _ := um.Resolve(cl.Username)
		rootAbs, _ := internal.SafeJoin(mediaRoot, rootRel)
		fromAbs, err := internal.SafeJoin(rootAbs, p.From)
		if err != nil {
			http.Error(w, "forbidden", http.StatusForbidden)
			return
		}
		toAbs, err := internal.SafeJoin(rootAbs, p.To)
		if err != nil {
			http.Error(w, "forbidden", http.StatusForbidden)
			return
		}
		_ = os.MkdirAll(filepath.Dir(toAbs), 0o755)
		if internal.DryRun {
			internal.Logf("[DRY] mv %s -> %s", fromAbs, toAbs)
		} else if err := os.Rename(fromAbs, toAbs); err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		jf.RefreshLibrary(cl.JFToken)
		_ = json.NewEncoder(w).Encode(map[string]any{"ok": true})
	})

	// delete
	r.Delete("/api/file", func(w http.ResponseWriter, r *http.Request) {
		cl, err := internal.CurrentUser(r)
		if err != nil {
			http.Error(w, "unauthorized", http.StatusUnauthorized)
			return
		}
		rootRel, _ := um.Resolve(cl.Username)
		path := r.URL.Query().Get("path")
		rec := r.URL.Query().Get("recursive") == "true"
		rootAbs, _ := internal.SafeJoin(mediaRoot, rootRel)
		abs, err := internal.SafeJoin(rootAbs, path)
		if err != nil {
			http.Error(w, "forbidden", http.StatusForbidden)
			return
		}
		if rec {
			err = os.RemoveAll(abs)
		} else {
			err = os.Remove(abs)
		}
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		jf.RefreshLibrary(cl.JFToken)
		_ = json.NewEncoder(w).Encode(map[string]any{"ok": true})
	})

	// mkdir (create subdirectory under the user's mapped root)
	r.Post("/api/mkdir", func(w http.ResponseWriter, r *http.Request) {
			cl, err := internal.CurrentUser(r)
			if err != nil { http.Error(w, "unauthorized", http.StatusUnauthorized); return }
			var p struct{ Path string `json:"path"` } // e.g., "Trips/2025-09"
			if err := json.NewDecoder(r.Body).Decode(&p); err != nil {
					http.Error(w, "bad json", http.StatusBadRequest); return
			}
			rootRel, err := um.Resolve(cl.Username)
			if err != nil { http.Error(w, "forbidden", http.StatusForbidden); return }
			rootAbs, _ := internal.SafeJoin(mediaRoot, rootRel)
			abs, err := internal.SafeJoin(rootAbs, strings.TrimPrefix(p.Path, "/"))
			if err != nil { http.Error(w, "forbidden", http.StatusForbidden); return }
			if internal.DryRun {
					internal.Logf("[DRY] mkdir -p %s", abs)
			} else if err := os.MkdirAll(abs, 0o755); err != nil {
					http.Error(w, err.Error(), http.StatusInternalServerError); return
			}
			_ = json.NewEncoder(w).Encode(map[string]any{"ok": true})
	})

	// mount tus (behind auth)
	r.Route("/tus", func(rt chi.Router) {
					rt.Use(sessionRequired)
					// Create upload: POST /tus/
					rt.Post("/", tusHandler.PostFile)
					// Upload resource endpoints: /tus/{id}
					rt.Head("/{id}", tusHandler.HeadFile)
					rt.Patch("/{id}", tusHandler.PatchFile)
					rt.Delete("/{id}", tusHandler.DelFile)
					rt.Get("/{id}", tusHandler.GetFile) // optional
	})
	// metrics
	r.Handle("/metrics", promhttp.Handler())

	// static app (serve embedded web/dist)
	appFS, _ := fs.Sub(webFS, "web/dist")
	static := http.FileServer(http.FS(appFS))
	r.Get("/", func(w http.ResponseWriter, r *http.Request) {
		static.ServeHTTP(w, r)
	})
	// catch-all for SPA routes, GET only
	r.Method("GET", "/*", http.StripPrefix("/", static))

	// debug endpoints (registered before server starts)
	r.Get("/debug/env", func(w http.ResponseWriter, r *http.Request) {
		if !internal.Debug {
			http.Error(w, "disabled", http.StatusForbidden)
			return
		}
		_ = json.NewEncoder(w).Encode(map[string]any{
			"mediaRoot":   mediaRoot,
			"tusDir":      tusDir,
			"userMapFile": userMapFile,
		})
	})
	r.Get("/debug/write-test", func(w http.ResponseWriter, r *http.Request) {
		if !internal.Debug {
			http.Error(w, "disabled", http.StatusForbidden)
			return
		}
		cl, err := internal.CurrentUser(r)
		if err != nil {
			http.Error(w, "unauthorized", http.StatusUnauthorized)
			return
		}
		rootRel, err := um.Resolve(cl.Username)
		if err != nil {
			http.Error(w, "forbidden", http.StatusForbidden)
			return
		}
		rootAbs, _ := internal.SafeJoin(mediaRoot, rootRel)
		test := filepath.Join(rootAbs, fmt.Sprintf("TEST.%d.txt", time.Now().Unix()))
		if internal.DryRun {
			internal.Logf("[DRY] write %s", test)
		} else {
			_ = os.WriteFile(test, []byte("ok\n"), 0o644)
		}
		_ = json.NewEncoder(w).Encode(map[string]string{"wrote": test})
	})

	r.NotFound(func(w http.ResponseWriter, r *http.Request) {
	    http.Error(w, "no route for "+r.Method+" "+r.URL.Path, http.StatusNotFound)
	})

	// ---- wrap router with verbose request logging in debug ----
	root := http.Handler(r)
	if internal.Debug {
		root = http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
			id := time.Now().UnixNano()
			internal.Logf(">> %d %s %s %v", id, req.Method, req.URL.Path, internal.RedactHeaders(req.Header))
			rw := &loggingRW{ResponseWriter: w, status: 200}
			start := time.Now()
			r.ServeHTTP(rw, req)
			internal.Logf("<< %d %s %s %d %s", id, req.Method, req.URL.Path, rw.status, time.Since(start))
		})
	}

	addr := env("PEGASUS_BIND", ":8080")
	log.Printf("Pegasus listening on %s", addr)
	srv := &http.Server{Addr: addr, Handler: root, ReadTimeout: 0, WriteTimeout: 0}
	log.Fatal(srv.ListenAndServe())
}

// === helpers & middleware ===
func sessionRequired(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if _, err := internal.CurrentUser(r); err != nil {
			http.Error(w, "unauthorized", http.StatusUnauthorized)
			return
		}
		next.ServeHTTP(w, r)
	})
}

func corsForTus(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// CORS for tus (preflight must succeed; cookies allowed)
		if origin := r.Header.Get("Origin"); origin != "" {
						w.Header().Set("Access-Control-Allow-Origin", origin) // cannot be * when credentials=true
						w.Header().Set("Vary", "Origin")
		}
		w.Header().Set("Access-Control-Allow-Credentials", "true")
		w.Header().Set("Access-Control-Allow-Methods", "GET,POST,HEAD,PATCH,DELETE,OPTIONS")
		w.Header().Set("Access-Control-Max-Age", "86400")
		w.Header().Set("Access-Control-Allow-Headers",
			  					"Content-Type, Tus-Resumable, Upload-Length, Upload-Defer-Length, Upload-Metadata, Upload-Offset, Upload-Concat, Upload-Checksum, X-Requested-With")
		w.Header().Set("Access-Control-Expose-Headers",
									"Location, Upload-Offset, Upload-Length, Tus-Resumable, Upload-Checksum")
		if r.Method == http.MethodOptions {
						w.WriteHeader(http.StatusNoContent)
						return
		}
		next.ServeHTTP(w, r)
	})
}

func claimsFromHook(ev tusd.HookEvent) (internal.Claims, error) {
	// Parse our session cookie from incoming request headers captured by tusd
	req := ev.HTTPRequest
	if req.Header == nil {
		return internal.Claims{}, http.ErrNoCookie
	}
	// Re-create a dummy http.Request to reuse cookie parsing & jwt verification
	r := http.Request{Header: http.Header(req.Header)}
	return internal.CurrentUser(&r)
}

func env(k, def string) string  { if v := os.Getenv(k); v != "" { return v }; return def }
func must(err error, msg string) { if err != nil { log.Fatalf("%s: %v", msg, err) } }