package db

import (
	"database/sql"
	"errors"
	"fmt"
	"os"
	"os/user"
	"path/filepath"

	_ "modernc.org/sqlite"
)

type DB struct {
	*sql.DB
	path string
}

var (
	database   *DB
	migrations = []string{
		`CREATE TABLE IF NOT EXISTS nodes (id TEXT PRIMARY KEY, title TEXT NOT NULL, content TEXT, due_date TEXT, created_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP, updated_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP)`,
		`CREATE TABLE IF NOT EXISTS tags (node_id TEXT NOT NULL, tag TEXT NOT NULL, PRIMARY KEY (node_id, tag), FOREIGN KEY (node_id) REFERENCES nodes(id) ON DELETE CASCADE)`,
		`CREATE TABLE IF NOT EXISTS rels (from_id TEXT NOT NULL, to_id TEXT NOT NULL, rel_type TEXT NOT NULL, PRIMARY KEY (from_id, to_id, rel_type), FOREIGN KEY (from_id) REFERENCES nodes(id) ON DELETE CASCADE, FOREIGN KEY (to_id) REFERENCES nodes(id) ON DELETE CASCADE)`,
		`CREATE TABLE IF NOT EXISTS aliases (name TEXT PRIMARY KEY, command TEXT NOT NULL)`,
		`CREATE INDEX IF NOT EXISTS idx_tags_tag ON tags(tag)`, `CREATE INDEX IF NOT EXISTS idx_rels_from ON rels(from_id)`, `CREATE INDEX IF NOT EXISTS idx_rels_to ON rels(to_id)`,
	}
)

func GetDB() (*DB, error) {
	if database != nil {
		return database, nil
	}
	dir, err := filepath.Abs(".")
	if err != nil {
		return nil, err
	}
	for {
		if _, err := os.Stat(filepath.Join(dir, ".ax.db")); err == nil {
			if database, err = Open(filepath.Join(dir, ".ax.db")); err != nil {
				return nil, fmt.Errorf("failed to open database: %w", err)
			}
			return database, nil
		}
		if parent := filepath.Dir(dir); parent == dir {
			return nil, errors.New("no .ax.db found (run 'ax init' first)")
		} else {
			dir = parent
		}
	}
}

func Init(path string) error {
	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
		return err
	}
	var err error
	database, err = Open(path)
	return err
}

func Open(path string) (*DB, error) {
	db, err := sql.Open("sqlite", path)
	if err != nil {
		return nil, err
	}
	for _, q := range append([]string{"PRAGMA journal_mode=WAL", "PRAGMA busy_timeout=5000", "PRAGMA foreign_keys=ON"}, migrations...) {
		if _, err := db.Exec(q); err != nil {
			return nil, err
		}
	}
	return &DB{DB: db, path: path}, nil
}

func GetCurrentUser() string {
	if u := os.Getenv("AX_USER"); u != "" {
		return u
	}
	if u, err := user.Current(); err == nil {
		return u.Username
	}
	return "unknown"
}