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import { ISubscription, NotSupported, QueryError } from '../interfaces.ts';import { Expr, ExprBinary, TableConstraintForeignKey } from 'https://deno.land/x/pgsql_ast_parser@12.0.1/mod.ts';import { asTable, CreateIndexColDef, _IConstraint, _ITable, _Transaction } from '../interfaces-private.ts';import { nullIsh } from '../utils.ts';
export class ForeignKey implements _IConstraint {
    private unsubs: ISubscription[] = [];
    private table!: _ITable;    private foreignTable!: _ITable;


    get db() {        return this.table.ownerSchema.db;    }
    get schema() {        return this.table.ownerSchema;    }

    constructor(readonly name: string) {    }
    install(_t: _Transaction, cst: TableConstraintForeignKey, table: _ITable) {        const ftable = asTable(table.ownerSchema.getObject(cst.foreignTable, { beingCreated: table }));        const cols = cst.localColumns.map(x => table.getColumnRef(x.name));        const fcols = cst.foreignColumns.map(x => ftable.getColumnRef(x.name));        this.table = table;        this.foreignTable = ftable;        if (cols.length !== fcols.length) {            throw new QueryError('Foreign key count mismatch');        }        cols.forEach((c, i) => {            if (fcols[i].expression.type !== c.expression.type) {                throw new QueryError(`Foreign key column type mismatch`);            }        });
        if ((cst.match ?? 'simple') !== 'simple' && cols.length !== 1) {            throw new NotSupported(`matching mode '${cst.match}' on mutliple columns foreign keys`);        }
        // check that there is an unique index on this table for the given expressions        const findex = ftable.getIndex(...fcols.map(x => x.expression));        if (!findex?.unique) {            throw new QueryError(`there is no unique constraint matching given keys for referenced table "${ftable.name}"`);        }

        // auto-create indices        if (this.db.options.autoCreateForeignKeyIndices) {            table.createIndex(_t, {                ifNotExists: true,                columns: cols.map<CreateIndexColDef>(x => ({                    value: x.expression,                })),            });        }
        // ========================        // when changing the foreign table key, check correspondances in this table        // ========================        const onUpdate = cst.onUpdate ?? 'no action';        const onDelete = cst.onDelete ?? 'no action';        this.unsubs.push(ftable.onBeforeChange(cst.foreignColumns.map(x => x.name), (old, neu, dt) => {            if (!old) {                return;            }            const oVals = fcols.map(x => old[x.expression.id!]);            if (oVals.some(nullIsh)) {                return;            }            // build foreign key equality expression            const equals = cst.localColumns.map<ExprBinary>((x, i) => ({                type: 'binary',                op: '=',                left: { type: 'ref', name: x.name, table: { name: table.name } },                // hack, see #fkcheck                right: {                    type: 'constant',                    value: oVals[i],                    dataType: fcols[i].expression.type as any, // hack                },            }));            const expr = equals.slice(1).reduce<Expr>((a, b) => ({                type: 'binary',                op: 'AND',                left: a,                right: b,            }), equals[0]);
            // check nothing matches            for (const local of table.selection.filter(expr).enumerate(dt)) {                // ====== ON DELETE                switch (neu ? onUpdate : onDelete) {                    case 'no action':                    case 'restrict':                        throw new QueryError(`update or delete on table "${ftable.name}" violates foreign key constraint on table "${this.name}"`);                    case 'cascade':                        if (neu) {                            for (let i = 0; i < fcols.length; i++) {                                local[cst.localColumns[i].name] = neu[cst.foreignColumns[i].name];                            }                            table.update(dt, local);                        } else {                            table.delete(dt, local);                        }                        break;                    case 'set default':                    case 'set null':                        for (const c of cst.localColumns) {                            local[c.name] = null;                        }                        table.update(dt, local);                        break;                }            }        }));
        // =====================        //  when changing something in this table,        //  then there must be a key match in the foreign table        // =====================        this.unsubs.push(table.onBeforeChange(cst.localColumns.map(x => x.name), (_, neu, dt) => {            if (!neu) {                return;            }            const vals = cols.map(x => (neu as any)[x.expression.id!]);            if (vals.some(nullIsh)) {                return;            }            // build foreign key equality expression            const equals = cst.foreignColumns.map<ExprBinary>((x, i) => ({                type: 'binary',                op: '=',                left: { type: 'ref', name: x.name, table: { name: ftable.name } },                // hack, see #fkcheck                right: {                    type: 'constant',                    value: vals[i],                    dataType: cols[i].expression.type as any, // hack                },            }));            const expr = equals.slice(1).reduce<Expr>((a, b) => ({                type: 'binary',                op: 'AND',                left: a,                right: b,            }), equals[0]);
            // check there is a match            let yielded = false;            for (const _ of ftable.selection.filter(expr).enumerate(dt)) {                yielded = true;            }            if (!yielded) {                throw new QueryError(`insert or update on table "${ftable.name}" violates foreign key constraint on table "${this.name}"`);            }        }));

        // =====================        //  prevent foreign table from being dropped        // =====================        this.unsubs.push(ftable.onDrop((t, cascade) => {            //  (todo implement multiple drops)            if (cascade) {                this.uninstall(t);            } else {                throw new QueryError({                    error: `cannot drop table "${ftable.name}" because other objects depend on it`,                    details: `constraint ${this.name} on table ${table.name} depends on table "${ftable.name}"`,                    hint: `Use DROP ... CASCADE to drop the dependent objects too.`,                });            }        }));
        // =====================        //  prevent foreign table truncation        // =====================        this.unsubs.push(ftable.onTruncate((t, { cascade }) => {            if (cascade) {                this.table.truncate(t, { cascade: true });                return;            }            throw new QueryError({                error: `cannot truncate a table referenced in a foreign key constraint`,                details: `Table "${table.name}" references "${ftable.name}".`,                hint: `HINT:  Truncate table "${table.name}" at the same time, or use TRUNCATE ... CASCADE.`,            })        }));
        // =====================        //  when this table is dropped => remove hooks on foreign table        // =====================        table.onDrop(dt => {            this.uninstall(dt);        });
        return this;    }
    uninstall(t: _Transaction): void {        this.unsubs.forEach(x => x.unsubscribe());        this.unsubs = [];    }}