package catalog

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"
	"time"
	"unicode"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
)

const maxUploadBytes = 5 << 20 // 5 MiB

func sanitizeFileName(name string) string {
	name = filepath.Base(strings.TrimSpace(name))
	if name == "" || name == "." || name == ".." {
		return "upload.csv"
	}
	var b strings.Builder
	for _, r := range name {
		if unicode.IsLetter(r) || unicode.IsDigit(r) || r == '.' || r == '-' || r == '_' {
			b.WriteRune(r)
		} else {
			b.WriteByte('_')
		}
	}
	out := b.String()
	if out == "" {
		return "upload.csv"
	}
	return out
}

func (s *Service) SaveUpload(ctx context.Context, companyID, userID uuid.UUID, uploadDir, originalName, contentType, kind string, r io.Reader) (map[string]any, error) {
	uploadDir = strings.TrimSpace(uploadDir)
	if uploadDir == "" {
		return nil, ClientMsg("upload directory not configured")
	}
	safe := sanitizeFileName(originalName)
	lower := strings.ToLower(safe)
	if !strings.HasSuffix(lower, ".csv") {
		return nil, ClientMsg("only .csv uploads are allowed")
	}
	if contentType != "" &&
		!strings.Contains(strings.ToLower(contentType), "csv") &&
		!strings.Contains(strings.ToLower(contentType), "text/plain") &&
		!strings.Contains(strings.ToLower(contentType), "octet-stream") {
		return nil, ClientMsg("invalid content type for CSV upload")
	}

	kind = strings.ToLower(strings.TrimSpace(kind))
	if kind == "" {
		kind = "products"
	}
	metaBytes, _ := json.Marshal(map[string]any{"kind": kind})

	fileID := uuid.New()
	dir := filepath.Join(uploadDir, companyID.String())
	if err := os.MkdirAll(dir, 0o750); err != nil {
		return nil, err
	}
	rel := filepath.ToSlash(filepath.Join(companyID.String(), fileID.String()+"-"+safe))
	abs := filepath.Join(uploadDir, filepath.FromSlash(rel))

	f, err := os.OpenFile(abs, os.O_CREATE|os.O_WRONLY|os.O_EXCL, 0o640)
	if err != nil {
		return nil, err
	}
	defer f.Close()

	n, err := io.Copy(f, io.LimitReader(r, maxUploadBytes+1))
	if err != nil {
		_ = os.Remove(abs)
		return nil, err
	}
	if n > maxUploadBytes {
		_ = os.Remove(abs)
		return nil, ClientMsg(fmt.Sprintf("file exceeds %d byte limit", maxUploadBytes))
	}

	var uid any
	if userID != uuid.Nil {
		uid = userID
	}

	var id uuid.UUID
	err = s.Pool.QueryRow(ctx, `
		INSERT INTO files (id, company_id, user_id, name, path, content_type, size_bytes, status, metadata)
		VALUES ($1, $2, $3, $4, $5, $6, $7, 'uploaded', $8::jsonb)
		RETURNING id`, fileID, companyID, uid, safe, rel, contentType, n, string(metaBytes)).Scan(&id)
	if err != nil {
		_ = os.Remove(abs)
		return nil, err
	}
	return map[string]any{
		"id":           id.String(),
		"name":         safe,
		"path":         rel,
		"content_type": contentType,
		"size_bytes":   n,
		"status":       "uploaded",
		"kind":         kind,
		"metadata":     map[string]any{"kind": kind},
	}, nil
}

func (s *Service) ResolveUploadPath(uploadDir string, companyID uuid.UUID, rel string) (string, error) {
	uploadDir = strings.TrimSpace(uploadDir)
	if uploadDir == "" {
		return "", ClientMsg("upload directory not configured")
	}
	rel = filepath.ToSlash(strings.TrimSpace(rel))
	if rel == "" || strings.Contains(rel, "..") {
		return "", ClientMsg("invalid path")
	}
	prefix := companyID.String() + "/"
	if !strings.HasPrefix(rel, prefix) {
		return "", ClientMsg("forbidden")
	}
	base, err := filepath.Abs(uploadDir)
	if err != nil {
		return "", err
	}
	abs, err := filepath.Abs(filepath.Join(uploadDir, filepath.FromSlash(rel)))
	if err != nil {
		return "", err
	}
	sep := string(os.PathSeparator)
	if abs != base && !strings.HasPrefix(abs, base+sep) {
		return "", ClientMsg("forbidden")
	}
	return abs, nil
}

func scanFileRow(rows pgx.Row) (map[string]any, error) {
	var (
		id          uuid.UUID
		companyID   uuid.UUID
		userID      *uuid.UUID
		name        string
		path        *string
		contentType *string
		sizeBytes   int64
		status      string
		metadata    []byte
		createdAt   time.Time
		updatedAt   time.Time
	)
	if err := rows.Scan(&id, &companyID, &userID, &name, &path, &contentType, &sizeBytes, &status, &metadata, &createdAt, &updatedAt); err != nil {
		return nil, err
	}
	var meta any = map[string]any{}
	if len(metadata) > 0 {
		_ = json.Unmarshal(metadata, &meta)
	}
	out := map[string]any{
		"id":         id.String(),
		"company_id": companyID.String(),
		"name":       name,
		"size_bytes": sizeBytes,
		"status":     status,
		"metadata":   meta,
		"created_at": createdAt.UTC().Format(time.RFC3339),
		"updated_at": updatedAt.UTC().Format(time.RFC3339),
	}
	if userID != nil {
		out["user_id"] = userID.String()
	}
	if path != nil {
		out["path"] = *path
	}
	if contentType != nil {
		out["content_type"] = *contentType
	}
	if m, ok := meta.(map[string]any); ok {
		if k, ok := m["kind"].(string); ok {
			out["kind"] = k
		}
	}
	return out, nil
}

func (s *Service) ListFiles(ctx context.Context, companyID uuid.UUID, f ListFilter) ([]map[string]any, int, error) {
	f = NormalizeListFilter(f)
	var total int
	if err := s.Pool.QueryRow(ctx, `SELECT COUNT(*) FROM files WHERE company_id = $1`, companyID).Scan(&total); err != nil {
		return nil, 0, err
	}
	rows, err := s.Pool.Query(ctx, `
		SELECT id, company_id, user_id, name, path, content_type, size_bytes, status, metadata, created_at, updated_at
		FROM files
		WHERE company_id = $1
		ORDER BY created_at DESC
		LIMIT $2 OFFSET $3`, companyID, f.Limit, f.Offset)
	if err != nil {
		return nil, 0, err
	}
	defer rows.Close()
	items := make([]map[string]any, 0)
	for rows.Next() {
		item, err := scanFileRow(rows)
		if err != nil {
			return nil, 0, err
		}
		items = append(items, item)
	}
	return items, total, rows.Err()
}

func (s *Service) GetFile(ctx context.Context, companyID, fileID uuid.UUID) (map[string]any, error) {
	row := s.Pool.QueryRow(ctx, `
		SELECT id, company_id, user_id, name, path, content_type, size_bytes, status, metadata, created_at, updated_at
		FROM files WHERE company_id = $1 AND id = $2`, companyID, fileID)
	item, err := scanFileRow(row)
	if errors.Is(err, pgx.ErrNoRows) {
		return nil, err
	}
	return item, err
}

func (s *Service) UpdateFileStatus(ctx context.Context, companyID, fileID uuid.UUID, status string, metadata map[string]any) (map[string]any, error) {
	status = strings.ToLower(strings.TrimSpace(status))
	switch status {
	case "uploaded", "processing", "completed", "failed":
	default:
		return nil, ClientMsg("invalid file status")
	}
	metaBytes := []byte("{}")
	if metadata != nil {
		b, err := json.Marshal(metadata)
		if err != nil {
			return nil, err
		}
		metaBytes = b
	}
	_, err := s.Pool.Exec(ctx, `
		UPDATE files
		SET status = $3,
		    metadata = COALESCE(metadata, '{}'::jsonb) || $4::jsonb,
		    updated_at = now()
		WHERE company_id = $1 AND id = $2`, companyID, fileID, status, string(metaBytes))
	if err != nil {
		return nil, err
	}
	return s.GetFile(ctx, companyID, fileID)
}

func (s *Service) DeleteFile(ctx context.Context, companyID, fileID uuid.UUID, uploadDir string) error {
	item, err := s.GetFile(ctx, companyID, fileID)
	if err != nil {
		return err
	}
	tag, err := s.Pool.Exec(ctx, `DELETE FROM files WHERE company_id = $1 AND id = $2`, companyID, fileID)
	if err != nil {
		return err
	}
	if tag.RowsAffected() == 0 {
		return pgx.ErrNoRows
	}
	if pathStr, ok := item["path"].(string); ok && pathStr != "" {
		if abs, err := s.ResolveUploadPath(uploadDir, companyID, pathStr); err == nil {
			_ = os.Remove(abs)
		}
	}
	return nil
}