package sqlite

import (
	"database/sql"
	"fmt"
	"sort"
	"strings"
	"time"

	"github.com/google/uuid"

	"task/internal/project"
)

// ProjectStore implements project.Store on SQLite.
type ProjectStore struct {
	db *DB
}

// NewProjectStore returns a project store.
func NewProjectStore(db *DB) *ProjectStore {
	return &ProjectStore{db: db}
}

// List returns all projects sorted by name.
func (s *ProjectStore) List() ([]project.Project, error) {
	rows, err := s.db.SQL.Query(`SELECT id, name FROM projects ORDER BY name COLLATE NOCASE`)
	if err != nil {
		return nil, fmt.Errorf("list projects: %w", err)
	}
	defer rows.Close()
	var out []project.Project
	for rows.Next() {
		var p project.Project
		if err := rows.Scan(&p.ID, &p.Name); err != nil {
			return nil, err
		}
		out = append(out, p)
	}
	if out == nil {
		out = []project.Project{}
	}
	return out, rows.Err()
}

// Ensure creates the project if missing.
func (s *ProjectStore) Ensure(id string) error {
	id = strings.TrimSpace(id)
	if id == "" {
		return fmt.Errorf("project id is required")
	}
	now := formatTime(time.Now().UTC())
	_, err := s.db.SQL.Exec(`
		INSERT INTO projects(id, name, created_at, updated_at) VALUES(?, ?, ?, ?)
		ON CONFLICT(id) DO NOTHING`, id, id, now, now)
	if err != nil {
		return fmt.Errorf("ensure project %s: %w", id, err)
	}
	return nil
}

// Create creates a project. Empty id is replaced with a new UUID.
func (s *ProjectStore) Create(id, name string) (project.Project, error) {
	id = strings.TrimSpace(id)
	name = strings.TrimSpace(name)
	if name == "" {
		return project.Project{}, fmt.Errorf("project name is required")
	}
	if id == "" {
		id = uuid.NewString()
	}
	now := formatTime(time.Now().UTC())
	_, err := s.db.SQL.Exec(`INSERT INTO projects(id, name, created_at, updated_at) VALUES(?, ?, ?, ?)`,
		id, name, now, now)
	if err != nil {
		return project.Project{}, fmt.Errorf("create project: %w", err)
	}
	return project.Project{ID: id, Name: name}, nil
}

// Rename updates the display name.
func (s *ProjectStore) Rename(id, name string) error {
	name = strings.TrimSpace(name)
	if id == "" || name == "" {
		return fmt.Errorf("id and name are required")
	}
	res, err := s.db.SQL.Exec(`UPDATE projects SET name = ?, updated_at = ? WHERE id = ?`,
		name, formatTime(time.Now().UTC()), id)
	if err != nil {
		return err
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return fmt.Errorf("project %s: not found", id)
	}
	return nil
}

// Delete removes a project and cascaded rows.
func (s *ProjectStore) Delete(id string) error {
	if id == "" {
		return fmt.Errorf("project id is required")
	}
	res, err := s.db.SQL.Exec(`DELETE FROM projects WHERE id = ?`, id)
	if err != nil {
		return fmt.Errorf("delete project %s: %w", id, err)
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return fmt.Errorf("project %s: not found", id)
	}
	return nil
}

// Get returns one project.
func (s *ProjectStore) Get(id string) (project.Project, error) {
	var p project.Project
	err := s.db.SQL.QueryRow(`SELECT id, name FROM projects WHERE id = ?`, id).Scan(&p.ID, &p.Name)
	if err == sql.ErrNoRows {
		return project.Project{}, fmt.Errorf("project %s: not found", id)
	}
	if err != nil {
		return project.Project{}, err
	}
	return p, nil
}

// LoadMeta maps sync_backends (+ connection token) into project.Meta.
func (s *ProjectStore) LoadMeta(id string) (project.Meta, error) {
	if id == "" {
		return project.Meta{}, fmt.Errorf("project id is required")
	}
	var kind, baseURL, projectKey, query string
	var connID sql.NullString
	err := s.db.SQL.QueryRow(`
		SELECT kind, base_url, project_key, query, connection_id
		FROM sync_backends WHERE project_id = ?`, id).
		Scan(&kind, &baseURL, &projectKey, &query, &connID)
	if err == sql.ErrNoRows {
		return project.Meta{}, nil
	}
	if err != nil {
		return project.Meta{}, fmt.Errorf("load meta %s: %w", id, err)
	}
	if kind != "youtrack" {
		return project.Meta{}, nil
	}
	yt := &project.YouTrack{
		BaseURL:    baseURL,
		ProjectKey: projectKey,
		Query:      query,
	}
	if connID.Valid && connID.String != "" {
		token, err := s.db.connectionToken(connID.String)
		if err != nil {
			return project.Meta{}, err
		}
		yt.Token = token
	}
	return project.Meta{YouTrack: yt}, nil
}

// SaveMeta writes YouTrack settings into sync_backends (creates inline connection if token set).
func (s *ProjectStore) SaveMeta(id string, meta project.Meta) error {
	if id == "" {
		return fmt.Errorf("project id is required")
	}
	if err := s.Ensure(id); err != nil {
		return err
	}
	if meta.YouTrack == nil || !meta.YouTrack.Configured() && strings.TrimSpace(meta.YouTrack.BaseURL) == "" {
		_, err := s.db.SQL.Exec(`DELETE FROM sync_backends WHERE project_id = ?`, id)
		return err
	}
	yt := meta.YouTrack
	var connID sql.NullString
	if strings.TrimSpace(yt.Token) != "" {
		cid, err := s.db.ensureProjectConnection(id, yt.BaseURL, yt.Token)
		if err != nil {
			return err
		}
		connID = sql.NullString{String: cid, Valid: true}
	}
	_, err := s.db.SQL.Exec(`
		INSERT INTO sync_backends(project_id, kind, base_url, project_key, query, connection_id)
		VALUES(?, 'youtrack', ?, ?, ?, ?)
		ON CONFLICT(project_id) DO UPDATE SET
			kind=excluded.kind,
			base_url=excluded.base_url,
			project_key=excluded.project_key,
			query=excluded.query,
			connection_id=COALESCE(excluded.connection_id, sync_backends.connection_id)`,
		id, yt.BaseURL, yt.ProjectKey, yt.Query, connID)
	return err
}

// SyncBackend is the persisted per-project sync config (API-facing).
type SyncBackend struct {
	ProjectID    string `json:"projectId"`
	Kind         string `json:"kind"`
	BaseURL      string `json:"baseUrl"`
	ProjectKey   string `json:"projectKey"`
	Query        string `json:"query,omitempty"`
	ConnectionID string `json:"connectionId,omitempty"`
}

// GetSyncBackend returns sync config for a project.
func (s *ProjectStore) GetSyncBackend(projectID string) (SyncBackend, error) {
	var b SyncBackend
	var connID sql.NullString
	err := s.db.SQL.QueryRow(`
		SELECT project_id, kind, base_url, project_key, query, connection_id
		FROM sync_backends WHERE project_id = ?`, projectID).
		Scan(&b.ProjectID, &b.Kind, &b.BaseURL, &b.ProjectKey, &b.Query, &connID)
	if err == sql.ErrNoRows {
		return SyncBackend{ProjectID: projectID, Kind: "none"}, nil
	}
	if err != nil {
		return SyncBackend{}, err
	}
	if connID.Valid {
		b.ConnectionID = connID.String
	}
	return b, nil
}

// SetSyncBackend upserts sync config.
func (s *ProjectStore) SetSyncBackend(b SyncBackend) error {
	if b.ProjectID == "" {
		return fmt.Errorf("projectId required")
	}
	if b.Kind == "" {
		b.Kind = "none"
	}
	var connID sql.NullString
	if b.ConnectionID != "" {
		connID = sql.NullString{String: b.ConnectionID, Valid: true}
	}
	_, err := s.db.SQL.Exec(`
		INSERT INTO sync_backends(project_id, kind, base_url, project_key, query, connection_id)
		VALUES(?, ?, ?, ?, ?, ?)
		ON CONFLICT(project_id) DO UPDATE SET
			kind=excluded.kind,
			base_url=excluded.base_url,
			project_key=excluded.project_key,
			query=excluded.query,
			connection_id=excluded.connection_id`,
		b.ProjectID, b.Kind, b.BaseURL, b.ProjectKey, b.Query, connID)
	return err
}

// ListIDsForUser returns project IDs the user can access (all if admin).
func (s *ProjectStore) ListIDsForUser(userID string, isAdmin bool) ([]project.Project, error) {
	if isAdmin {
		return s.List()
	}
	rows, err := s.db.SQL.Query(`
		SELECT p.id, p.name FROM projects p
		INNER JOIN project_members m ON m.project_id = p.id
		WHERE m.user_id = ?
		ORDER BY p.name COLLATE NOCASE`, userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []project.Project
	for rows.Next() {
		var p project.Project
		if err := rows.Scan(&p.ID, &p.Name); err != nil {
			return nil, err
		}
		out = append(out, p)
	}
	if out == nil {
		out = []project.Project{}
	}
	sort.Slice(out, func(i, j int) bool { return out[i].Name < out[j].Name })
	return out, rows.Err()
}

func (db *DB) ensureProjectConnection(projectID, baseURL, token string) (string, error) {
	// Reuse existing sync_backends connection if present.
	var existing sql.NullString
	_ = db.SQL.QueryRow(`SELECT connection_id FROM sync_backends WHERE project_id = ?`, projectID).Scan(&existing)
	if existing.Valid && existing.String != "" {
		enc, err := db.EncryptToken(token)
		if err != nil {
			return "", err
		}
		_, err = db.SQL.Exec(`UPDATE connections SET encrypted_token = ?, base_url = ? WHERE id = ?`,
			enc, baseURL, existing.String)
		if err != nil {
			return "", err
		}
		return existing.String, nil
	}
	id := "conn_" + projectID
	enc, err := db.EncryptToken(token)
	if err != nil {
		return "", err
	}
	_, err = db.SQL.Exec(`
		INSERT INTO connections(id, name, kind, base_url, scope, encrypted_token, created_by, created_at)
		VALUES(?, ?, 'youtrack', ?, 'project', ?, NULL, ?)
		ON CONFLICT(id) DO UPDATE SET encrypted_token=excluded.encrypted_token, base_url=excluded.base_url`,
		id, "project:"+projectID, baseURL, enc, formatTime(time.Now().UTC()))
	if err != nil {
		return "", err
	}
	return id, nil
}

func (db *DB) connectionToken(id string) (string, error) {
	var blob []byte
	err := db.SQL.QueryRow(`SELECT encrypted_token FROM connections WHERE id = ?`, id).Scan(&blob)
	if err == sql.ErrNoRows {
		return "", fmt.Errorf("connection %s not found", id)
	}
	if err != nil {
		return "", err
	}
	return db.DecryptToken(blob)
}