package database

import (
	"database/sql"
	"fmt"
	"log"

	_ "github.com/mattn/go-sqlite3"
)

func InitDB(db *sql.DB) {
	schema := `
    CREATE TABLE IF NOT EXISTS currencies (
        id   INTEGER PRIMARY KEY AUTOINCREMENT,
        code TEXT    NOT NULL UNIQUE,
        name TEXT    NOT NULL
    );

    CREATE TABLE IF NOT EXISTS companies (
        id                 INTEGER PRIMARY KEY AUTOINCREMENT,
        name               TEXT    NOT NULL UNIQUE,
        shares_outstanding INTEGER NOT NULL,
        price              REAL    NOT NULL,
        currency_id        INTEGER NOT NULL,
        FOREIGN KEY (currency_id) REFERENCES currencies(id)
    );

    CREATE TABLE IF NOT EXISTS periods (
        id         INTEGER PRIMARY KEY AUTOINCREMENT,
        type       TEXT    NOT NULL CHECK(type IN ('Q', 'H', 'Y')),
        year       INTEGER NOT NULL,
        idx        INTEGER NOT NULL,
        start_date TEXT    NOT NULL,
        end_date   TEXT    NOT NULL,
        UNIQUE(type, year, idx)
    );

    CREATE TABLE IF NOT EXISTS category (
        id         INTEGER PRIMARY KEY AUTOINCREMENT,
        company_id INTEGER NOT NULL,
        parent_id  INTEGER,
        name       TEXT    NOT NULL,
        FOREIGN KEY (company_id) REFERENCES companies(id),
        FOREIGN KEY (parent_id)  REFERENCES category(id),
        UNIQUE(company_id, name)
    );

    CREATE TABLE IF NOT EXISTS revenue_entries (
        id          INTEGER PRIMARY KEY AUTOINCREMENT,
        company_id  INTEGER NOT NULL,
        currency_id INTEGER NOT NULL,
        category_id INTEGER NOT NULL,
        period_id   INTEGER NOT NULL,
        value       REAL    NOT NULL,
        FOREIGN KEY (company_id)  REFERENCES companies(id),
        FOREIGN KEY (currency_id) REFERENCES currencies(id),
        FOREIGN KEY (category_id) REFERENCES category(id),
        FOREIGN KEY (period_id)   REFERENCES periods(id),
        UNIQUE(company_id, category_id, period_id)
    );`

	if _, err := db.Exec(schema); err != nil {
		log.Fatal("Failed to create tables:", err)
	}
	fmt.Println("Tables ready")
}

func MigrateAddUniqueToRevenueEntries(db *sql.DB) error {
	steps := []string{
		// 1. copy existing data into a temp table with the new constraint
		`CREATE TABLE IF NOT EXISTS revenue_entries_new (
			id          INTEGER PRIMARY KEY AUTOINCREMENT,
			company_id  INTEGER NOT NULL,
			currency_id INTEGER NOT NULL,
			category_id INTEGER NOT NULL,
			period_id   INTEGER NOT NULL,
			value       REAL    NOT NULL,
			FOREIGN KEY (company_id)  REFERENCES companies(id),
			FOREIGN KEY (currency_id) REFERENCES currencies(id),
			FOREIGN KEY (category_id) REFERENCES category(id),
			FOREIGN KEY (period_id)   REFERENCES periods(id),
			UNIQUE(company_id, category_id, period_id)
		)`,
		// 2. copy data over
		`INSERT OR IGNORE INTO revenue_entries_new
			SELECT id, company_id, currency_id, category_id, period_id, value
			FROM revenue_entries`,
		// 3. drop old table
		`DROP TABLE revenue_entries`,
		// 4. rename new table
		`ALTER TABLE revenue_entries_new RENAME TO revenue_entries`,
	}

	for _, step := range steps {
		if _, err := db.Exec(step); err != nil {
			return fmt.Errorf("migration failed: %w", err)
		}
	}
	return nil
}