package core

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

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

type Item struct {
	source  string
	id      string
	created int
	active  bool
	title   string
	author  string
	body    string
	link    string
	time    int
}

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

// Idempotently initialize the database. Safe to call unconditionally.
func InitDatabase(db *sql.DB) error {
	rows, err := db.Query(`
		select exists (
			select 1
			from sqlite_master
			where type = 'table'
			and name = 'migrations'
		)
	`)
	if err != nil {
		return err
	}

	var exists bool
	for rows.Next() {
		rows.Scan(&exists)
	}

	if exists {
		return nil
	}

	err = ApplyMigration(db, "0000_baseline.sql")
	return err
}

// Get the names of existing migrations that haven't been applied yet.
func GetPendingMigrations(db *sql.DB) ([]string, error) {
	allMigrations, err := migrations.ReadDir("sql")
	if err != nil {
		return nil, err
	}

	complete := map[string]bool{}
	for _, mig := range allMigrations {
		complete[mig.Name()] = false
	}

	rows, err := db.Query("select name from migrations")
	if err != nil {
		return nil, err
	}
	for rows.Next() {
		var name string
		rows.Scan(&name)
		complete[name] = true
	}

	var pending []string
	for name, isComplete := range complete {
		if !isComplete {
			pending = append(pending, name)
		}
	}

	return pending, nil
}

// Apply a migration by name.
func ApplyMigration(db *sql.DB, name string) error {
	data, err := migrations.ReadFile("sql/" + name)
	if err != nil {
		log.Fatalf("Missing migration %s", name)
	}
	log.Printf("Applying migration %s", name)
	_, err = db.Exec(string(data))
	if err != nil {
		return err
	}
	_, err = db.Exec("insert into migrations (name) values (?)", name)
	return err
}

// Apply all pending migrations.
func MigrateDatabase(db *sql.DB) error {
	pending, err := GetPendingMigrations(db)
	if err != nil {
		return err
	}
	for _, name := range pending {
		err = ApplyMigration(db, name)
		if err != nil {
			return err
		}
	}
	return nil
}

func AddSource(db *sql.DB, name string) error {
	_, err := db.Exec(`
		insert into sources (name)
		values (?)
	`, name)

	return err
}

func DeleteSource(db *sql.DB, name string) error {
	_, err := db.Exec(`
	delete from sources
	where name = ?
	`, name)

	return err
}

func AddItem(
	db *sql.DB,
	source string,
	id string,
	title string,
	author string,
	body string,
	link string,
	time int,
) error {
	_, err := db.Exec(`
		insert into items (source, id, active, title, author, body, link, time)
		values (?, ?, ?, ?, ?, ?, ?, ?)
	`, source, id, true, title, author, body, link, time)

	return err
}

func DeactivateItem(db *sql.DB, source string, id string) error {
	res, err := db.Exec(`
		update items
		set active = 0
		where source = ? and id = ?
	`, source, id)
	if err != nil {
		return err
	}
	num, err := res.RowsAffected()
	if err != nil {
		return err
	}
	if num == 0 {
		return fmt.Errorf("item %s/%s not found", source, id)
	}
	return nil
}

func GetActiveItems(db *sql.DB, source string) ([]Item, error) {
	rows, err := db.Query(`
		select
			source,
			id,
			created,
			active,
			title,
			author,
			body,
			link,
			time
		from items
		where
			source = ?
		and active <> 0
	`, source)
	if err != nil {
		return nil, err
	}
	var items []Item
	for rows.Next() {
		var item Item
		rows.Scan(&item.source, &item.id, &item.created, &item.active, &item.title, &item.author, &item.body, &item.link, &item.time)
		items = append(items, item)
	}
	return items, nil
}