import {Schema} from './Schema'
import {SQLiteConnection} from '../connection/SQLiteConnection'
import {Awaitable} from '../../util'
import {TableBuilder} from './TableBuilder'
import {Builder} from '../builder/Builder'
import {raw} from '../dialect/SQLDialect'

export class SQLiteSchema extends Schema {
    constructor(
        connection: SQLiteConnection,
    ) {
        super(connection)
    }

    hasColumn(table: string, name: string): Awaitable<boolean> {
        return (new Builder()).connection(this.connection)
            .select(raw('*'))
            .from(`pragma_table_info(${this.connection.dialect().escape(table)})`)  // FIXME: probably needs to be raw(...)
            .where('name', '=', name)
            .exists()
    }

    hasColumns(table: string, name: string[]): Awaitable<boolean> {
        return (new Builder()).connection(this.connection)
            .select(raw('*'))
            .from(`pragma_table_info(${this.connection.dialect().escape(table)})`)  // FIXME: probably needs to be raw(...)
            .whereIn('name', name)
            .get()
            .count()
            .then(num => num === name.length)
    }

    hasTable(name: string): Awaitable<boolean> {
        return (new Builder()).connection(this.connection)
            .select(raw('*'))
            .from('sqlite_master')
            .where('type', '=', 'table')
            .where('name', '=', name)
            .exists()
    }

    table(table: string): Awaitable<TableBuilder> {
        return this.populateTable(new TableBuilder(table))
    }

    protected async populateTable(table: TableBuilder): Promise<TableBuilder> {
        if ( !(await this.hasTable(table.name)) ) {
            return table
        }

        // Load the existing columns
        await (new Builder()).connection(this.connection)
            .select(raw('*'))
            .from(raw(`pragma_table_info(${this.connection.dialect().escape(table.name)})`))
            .get()
            .each(col => {
                table.column(col.name)
                    .type(col.type)
                    .pipe(line => {
                        return line.unless(col.notnull, builder => builder.nullable())
                            .when(col.dflt_value, builder => builder.default(raw(col.dflt_value)))
                            .when(col.pk, builder => builder.primary())
                    })
                    .flagAsExistingInSchema()
            })

        // TODO: Load the existing constraints
        // TODO: Look up and apply the check constraints

        // Look up table indexes
        await (new Builder()).connection(this.connection)
            .select(raw('*'))
            .from(raw(`pragma_index_list(${this.connection.dialect().escape(table.name)})`))
            .get()
            .each(async idx => {
                const indexBuilder = table.index(idx.name)
                    .pipe(line => line.when(idx.unique, builder => builder.unique()))

                const idxColumns = await (new Builder()).connection(this.connection)
                    .select(raw('*'))
                    .from(raw(`pragma_index_xinfo(${this.connection.dialect().escape(idx.name)})`))
                    .whereNotNull('name')
                    .get()
                    .pluck('name')

                idxColumns.whereDefined()
                    .each(col => indexBuilder.field(col))

                indexBuilder.flagAsExistingInSchema()
            })

        return table.flagAsExistingInSchema()
    }
}