// Package postgres implements the storage interfaces on PostgreSQL 15+ via
// pgx's database/sql driver. This is the production backend and the one
// Complement runs against.
package postgres

import (
	"context"
	"database/sql"
	"embed"
	"fmt"
	"log/slog"
	"strings"

	_ "github.com/jackc/pgx/v5/stdlib" // registers the "pgx" database/sql driver

	"github.com/dariuszjaniak/warp/server/internal/storage"
	"github.com/dariuszjaniak/warp/server/internal/storage/migrations"
	"github.com/dariuszjaniak/warp/server/internal/storage/sqlstore"
)

//go:embed migrations/*.sql
var migrationFiles embed.FS

func init() {
	storage.Register(storage.DriverPostgres, Open)
}

var dialect = migrations.Dialect{
	Name: storage.DriverPostgres,
	CreateTable: `CREATE TABLE IF NOT EXISTS schema_migrations (
		version    INTEGER     PRIMARY KEY,
		name       TEXT        NOT NULL,
		checksum   TEXT        NOT NULL,
		applied_at TIMESTAMPTZ NOT NULL
	)`,
	SelectApplied: `SELECT version, name, checksum, applied_at FROM schema_migrations ORDER BY version`,
	InsertApplied: `INSERT INTO schema_migrations (version, name, checksum, applied_at) VALUES ($1, $2, $3, $4)`,
}

var settingsQueries = sqlstore.SettingsQueries{
	Get:    `SELECT setting_value FROM server_settings WHERE setting_key = $1`,
	GetAll: `SELECT setting_key, setting_value FROM server_settings`,
	Upsert: `INSERT INTO server_settings (setting_key, setting_value, updated_at) VALUES ($1, $2, $3)
		ON CONFLICT (setting_key) DO UPDATE SET setting_value = excluded.setting_value, updated_at = excluded.updated_at`,
	Delete: `DELETE FROM server_settings WHERE setting_key = $1`,
}

// searchDialect is the full-text index on tsvector, with the 'simple'
// configuration the migration builds the column with.
var searchDialect = &sqlstore.SearchDialect{
	Insert: `INSERT INTO roomserver_event_search (stream_ordering, room_id, event_id, search_key, sender, event_type, body)
		VALUES (?, ?, ?, ?, ?, ?, ?) ON CONFLICT (stream_ordering) DO NOTHING`,
	DeleteEvent: `DELETE FROM roomserver_event_search WHERE room_id = ? AND event_id = ?`,
	DeleteRoom:  `DELETE FROM roomserver_event_search WHERE room_id = ?`,
	From:        `roomserver_event_search s`,
	Name:        `s`,
	Position:    `s.stream_ordering`,
	Match:       `s.vector @@ to_tsquery('simple', ?)`,
	Rank:        `ts_rank(s.vector, to_tsquery('simple', ?))`,
	RankArgs:    1,
	Query:       tsQuery,
}

// tsQuery builds a tsquery from a search term: every word as a prefix
// match, ANDed. The words are letters and digits only, so none of them can
// carry tsquery syntax of its own.
func tsQuery(term string) string {
	words := storage.SearchWords(term)
	for i, w := range words {
		words[i] = w + ":*"
	}
	return strings.Join(words, " & ")
}

// Database is the PostgreSQL implementation of storage.Database.
type Database struct {
	*sqlstore.Store
}

// Open connects to the DSN in cfg.ConnectionString, e.g.
// "postgres://warp:secret@localhost/warp?sslmode=disable".
func Open(ctx context.Context, cfg storage.Config, log *slog.Logger) (storage.Database, error) {
	if cfg.ConnectionString == "" {
		return nil, fmt.Errorf("postgres: connection_string must not be empty")
	}
	db, err := sql.Open("pgx", cfg.ConnectionString)
	if err != nil {
		return nil, err
	}
	db.SetMaxOpenConns(cfg.MaxOpenConns)
	db.SetMaxIdleConns(cfg.MaxIdleConns)
	db.SetConnMaxLifetime(cfg.ConnMaxLifetime)

	if err := db.PingContext(ctx); err != nil {
		_ = db.Close()
		return nil, fmt.Errorf("postgres: connect: %w", err)
	}

	store, err := sqlstore.New(sqlstore.Options{
		DriverName:        storage.DriverPostgres,
		DB:                db,
		Dialect:           dialect,
		MigrationsFS:      migrationFiles,
		MigrationsDir:     "migrations",
		Settings:          settingsQueries,
		Rebind:            rebind,
		IsUniqueViolation: isUniqueViolation,
		Search:            searchDialect,
		Logger:            log,
	})
	if err != nil {
		_ = db.Close()
		return nil, err
	}
	return &Database{Store: store}, nil
}