package sqlite

import (
	"database/sql"

	_ "github.com/mattn/go-sqlite3"
	"github.com/mickael-menu/zk/util/errors"
)

// DB holds the connections to a SQLite database.
type DB struct {
	db *sql.DB
}

// Open creates a new DB instance for the SQLite database at the given path.
func Open(path string) (*DB, error) {
	return open("file:" + path)
}

// OpenInMemory creates a new in-memory DB instance.
func OpenInMemory() (*DB, error) {
	return open(":memory:")
}

func open(uri string) (*DB, error) {
	wrap := errors.Wrapper("failed to open the database")

	db, err := sql.Open("sqlite3", uri)
	if err != nil {
		return nil, wrap(err)
	}

	// Make sure that CASCADE statements are properly applied by enabling
	// foreign keys.
	_, err = db.Exec("PRAGMA foreign_keys = ON")
	if err != nil {
		return nil, wrap(err)
	}

	return &DB{db}, nil
}

// Close terminates the connections to the SQLite database.
func (db *DB) Close() error {
	err := db.db.Close()
	return errors.Wrap(err, "failed to close the database")
}

// Migrate upgrades the SQL schema of the database.
func (db *DB) Migrate() error {
	err := db.WithTransaction(func(tx Transaction) error {
		var version int
		err := tx.QueryRow("PRAGMA user_version").Scan(&version)
		if err != nil {
			return err
		}

		if version == 0 {
			err = tx.ExecStmts([]string{
				// Notes
				`CREATE TABLE IF NOT EXISTS notes (
					id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
					path TEXT NOT NULL,
					sortable_path TEXT NOT NULL,
					title TEXT DEFAULT('') NOT NULL,
					lead TEXT DEFAULT('') NOT NULL,
					body TEXT DEFAULT('') NOT NULL,
					raw_content TEXT DEFAULT('') NOT NULL,
					word_count INTEGER DEFAULT(0) NOT NULL,
					checksum TEXT NOT NULL,
					created DATETIME DEFAULT(CURRENT_TIMESTAMP) NOT NULL,
					modified DATETIME DEFAULT(CURRENT_TIMESTAMP) NOT NULL,
					UNIQUE(path)
				)`,
				`CREATE INDEX IF NOT EXISTS index_notes_checksum ON notes (checksum)`,
				`CREATE INDEX IF NOT EXISTS index_notes_path ON notes (path)`,

				// Links
				`CREATE TABLE IF NOT EXISTS links (
					id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
					source_id INTEGER NOT NULL REFERENCES notes(id)
						ON DELETE CASCADE,
					target_id INTEGER REFERENCES notes(id)
						ON DELETE SET NULL,
					title TEXT DEFAULT('') NOT NULL,
					href TEXT NOT NULL,
					external INT DEFAULT(0) NOT NULL,
					rels TEXT DEFAULT('') NOT NULL,
					snippet TEXT DEFAULT('') NOT NULL
				)`,
				`CREATE INDEX IF NOT EXISTS index_links_source_id_target_id ON links (source_id, target_id)`,

				// FTS index
				`CREATE VIRTUAL TABLE IF NOT EXISTS notes_fts USING fts5(
					path, title, body,
					content = notes,
					content_rowid = id,
					tokenize = "porter unicode61 remove_diacritics 1 tokenchars '''&/'"
				)`,
				// Triggers to keep the FTS index up to date.
				`CREATE TRIGGER IF NOT EXISTS trigger_notes_ai AFTER INSERT ON notes BEGIN
					INSERT INTO notes_fts(rowid, path, title, body) VALUES (new.id, new.path, new.title, new.body);
				END`,
				`CREATE TRIGGER IF NOT EXISTS trigger_notes_ad AFTER DELETE ON notes BEGIN
					INSERT INTO notes_fts(notes_fts, rowid, path, title, body) VALUES('delete', old.id, old.path, old.title, old.body);
				END`,
				`CREATE TRIGGER IF NOT EXISTS trigger_notes_au AFTER UPDATE ON notes BEGIN
					INSERT INTO notes_fts(notes_fts, rowid, path, title, body) VALUES('delete', old.id, old.path, old.title, old.body);
					INSERT INTO notes_fts(rowid, path, title, body) VALUES (new.id, new.path, new.title, new.body);
				END`,
				`PRAGMA user_version = 1`,
			})

			if err != nil {
				return err
			}
		}

		return nil
	})

	return errors.Wrap(err, "database migration failed")
}