// cmd/shard/main.go
package main

import (
	"crypto/sha256"
	"encoding/hex"
	"io"
	"log"
	"os"
	"path/filepath"
	"strings"
	"syscall"
	"time"

	"greencoast/internal/api"
	"greencoast/internal/index"

	"gopkg.in/yaml.v3"
)

type cfgPrivacy struct {
	AllowAnonPlaintext bool `yaml:"allow_anon_plaintext"`
}
type shardConfig struct {
	Privacy cfgPrivacy `yaml:"privacy"`
}

func boolEnv(keys ...string) bool {
	for _, k := range keys {
		v := strings.ToLower(strings.TrimSpace(os.Getenv(k)))
		if v == "1" || v == "true" || v == "yes" || v == "on" {
			return true
		}
	}
	return false
}

func loadYAMLAllow(path string) bool {
	f, err := os.Open(path)
	if err != nil {
		return false
	}
	defer f.Close()
	var sc shardConfig
	if err := yaml.NewDecoder(f).Decode(&sc); err != nil {
		return false
	}
	return sc.Privacy.AllowAnonPlaintext
}

/* -------------------------
   Minimal FS blob store (implements api.BlobStore)
   Layout:
     /var/lib/greencoast/objects/<hash>       content
     /var/lib/greencoast/objects/<hash>.priv  empty sidecar => private
--------------------------*/

type fsStore struct {
	root string
}

func newFSStore(root string) *fsStore { return &fsStore{root: root} }

func (s *fsStore) ensureRoot() error {
	// create both parent and leaf to be safe on fresh volumes
	if err := os.MkdirAll(filepath.Dir(s.root), 0o755); err != nil {
		return err
	}
	return os.MkdirAll(s.root, 0o755)
}
func (s *fsStore) pathFor(hash string) string     { return filepath.Join(s.root, hash) }
func (s *fsStore) privPathFor(hash string) string { return filepath.Join(s.root, hash+".priv") }

func (s *fsStore) Get(hash string) (io.ReadCloser, int64, error) {
	if err := s.ensureRoot(); err != nil {
		return nil, 0, err
	}
	f, err := os.Open(s.pathFor(hash))
	if err != nil {
		return nil, 0, err
	}
	st, err := f.Stat()
	if err != nil {
		_ = f.Close()
		return nil, 0, err
	}
	return f, st.Size(), nil
}

func (s *fsStore) Put(r io.Reader, private bool) (string, int64, time.Time, error) {
	if err := s.ensureRoot(); err != nil {
		return "", 0, time.Time{}, err
	}

	tmp, err := os.CreateTemp(s.root, "put-*")
	if err != nil {
		return "", 0, time.Time{}, err
	}
	tmpName := tmp.Name()
	defer func() {
		// best-effort cleanup of temp path (original name)
		_ = os.Remove(tmpName)
	}()

	h := sha256.New()
	w := io.MultiWriter(tmp, h)
	n, err := io.Copy(w, r)
	if err != nil {
		_ = tmp.Close()
		return "", 0, time.Time{}, err
	}

	// IMPORTANT on Windows bind mounts: flush & close before rename
	if err := tmp.Sync(); err != nil {
		_ = tmp.Close()
		return "", 0, time.Time{}, err
	}
	if err := tmp.Close(); err != nil {
		return "", 0, time.Time{}, err
	}

	hash := hex.EncodeToString(h.Sum(nil))
	final := s.pathFor(hash)

	// If a previous file with this hash exists, remove it first (idempotent writes)
	_ = os.Remove(final)

	if err := os.Rename(tmpName, final); err != nil {
		return "", 0, time.Time{}, err
	}

	// Optional: fsync directory to harden the rename on some filesystems
	if df, err := os.Open(s.root); err == nil {
		_ = syscall.Fsync(int(df.Fd()))
		_ = df.Close()
	}

	st, err := os.Stat(final)
	if err != nil {
		return "", 0, time.Time{}, err
	}

	// create sidecar only after main content is durable
	if private {
		if err := os.WriteFile(s.privPathFor(hash), nil, 0o600); err != nil {
			_ = os.Remove(final)
			return "", 0, time.Time{}, err
		}
	}

	return hash, n, st.ModTime().UTC(), nil
}

func (s *fsStore) Delete(hash string) error {
	if err := s.ensureRoot(); err != nil {
		return err
	}
	_ = os.Remove(s.privPathFor(hash))
	return os.Remove(s.pathFor(hash))
}

func (s *fsStore) Walk(fn func(hash string, bytes int64, private bool, storedAt time.Time) error) (int, error) {
	if err := s.ensureRoot(); err != nil {
		return 0, err
	}
	ents, err := os.ReadDir(s.root)
	if err != nil {
		return 0, err
	}
	count := 0
	for _, e := range ents {
		if e.IsDir() {
			continue
		}
		name := e.Name()
		// skip sidecars and non-64-hex filenames
		if strings.HasSuffix(name, ".priv") || len(name) != 64 || !isHex(name) {
			continue
		}
		full := s.pathFor(name)
		st, err := os.Stat(full)
		if err != nil {
			continue
		}
		private := false
		if _, err := os.Stat(s.privPathFor(name)); err == nil {
			private = true
		}
		if err := fn(name, st.Size(), private, st.ModTime().UTC()); err != nil {
			return count, err
		}
		count++
	}
	return count, nil
}

func isHex(s string) bool {
	for i := 0; i < len(s); i++ {
		c := s[i]
		if !((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F')) {
			return false
		}
	}
	return true
}

/* -------------------------
   main
--------------------------*/

func main() {
	// Store & index
	store := newFSStore("/var/lib/greencoast/objects")
	idx := index.New()

	// Flags: env wins, else YAML (/app/shard.yaml), else false
	allowAnon := boolEnv("GC_ALLOW_ANON_PLAINTEXT")
	if !allowAnon {
		if st, err := os.Stat("/app/shard.yaml"); err == nil && !st.IsDir() {
			allowAnon = loadYAMLAllow("/app/shard.yaml")
		}
	}
	devMode := boolEnv("GC_DEV_ALLOW_UNAUTH")

	log.Printf("boot: privacy.allow_anon_plaintext=%v  dev=%v  at=%s", allowAnon, devMode, time.Now().UTC().Format(time.RFC3339))

	var providers api.AuthProviders
	srv := api.New(store, idx, true, devMode, providers, allowAnon)

	// Frontend (static)
	go func() {
		if err := srv.ListenFrontend("0.0.0.0:9082"); err != nil {
			log.Printf("frontend server exited: %v", err)
		}
	}()

	// API
	if err := srv.ListenHTTP("0.0.0.0:9080"); err != nil {
		log.Fatal(err)
	}
}