import { ColumnMetadata } from "../metadata/ColumnMetadata"
import { UniqueMetadata } from "../metadata/UniqueMetadata"
import { ForeignKeyMetadata } from "../metadata/ForeignKeyMetadata"
import { RelationMetadata } from "../metadata/RelationMetadata"
import { JoinColumnMetadataArgs } from "../metadata-args/JoinColumnMetadataArgs"
import { DataSource } from "../data-source/DataSource"
import { TypeORMError } from "../error"
import { DriverUtils } from "../driver/DriverUtils"

/**
 * Builds join column for the many-to-one and one-to-one owner relations.
 *
 * Cases it should cover:
 * 1. when join column is set with custom name and without referenced column name
 * we need automatically set referenced column name - primary ids by default
 * @JoinColumn({ name: "custom_name" })
 *
 * 2. when join column is set with only referenced column name
 * we need automatically set join column name - relation name + referenced column name
 * @JoinColumn({ referencedColumnName: "title" })
 *
 * 3. when join column is set without both referenced column name and join column name
 * we need to automatically set both of them
 * @JoinColumn()
 *
 * 4. when join column is not set at all (as in case of @ManyToOne relation)
 * we need to create join column for it with proper referenced column name and join column name
 *
 * 5. when multiple join columns set none of referencedColumnName and name can be optional
 * both options are required
 * @JoinColumn([
 *      { name: "category_title", referencedColumnName: "type" },
 *      { name: "category_title", referencedColumnName: "name" },
 * ])
 *
 * Since for many-to-one relations having JoinColumn decorator is not required,
 * we need to go through each many-to-one relation without join column decorator set
 * and create join column metadata args for them.
 */
export class RelationJoinColumnBuilder {
    // -------------------------------------------------------------------------
    // Constructor
    // -------------------------------------------------------------------------

    constructor(private connection: DataSource) {}

    // -------------------------------------------------------------------------
    // Public Methods
    // -------------------------------------------------------------------------

    /**
     * Builds a foreign key of the many-to-one or one-to-one owner relations.
     */
    build(
        joinColumns: JoinColumnMetadataArgs[],
        relation: RelationMetadata,
    ): {
        foreignKey: ForeignKeyMetadata | undefined
        columns: ColumnMetadata[]
        uniqueConstraint: UniqueMetadata | undefined
    } {
        const referencedColumns = this.collectReferencedColumns(
            joinColumns,
            relation,
        )
        const columns = this.collectColumns(
            joinColumns,
            relation,
            referencedColumns,
        )
        if (!referencedColumns.length || !relation.createForeignKeyConstraints)
            return {
                foreignKey: undefined,
                columns,
                uniqueConstraint: undefined,
            } // this case is possible for one-to-one non owning side and relations with createForeignKeyConstraints = false

        const foreignKey = new ForeignKeyMetadata({
            name: joinColumns[0]?.foreignKeyConstraintName,
            entityMetadata: relation.entityMetadata,
            referencedEntityMetadata: relation.inverseEntityMetadata,
            namingStrategy: this.connection.namingStrategy,
            columns,
            referencedColumns,
            onDelete: relation.onDelete,
            onUpdate: relation.onUpdate,
            deferrable: relation.deferrable,
        })

        // SQL requires UNIQUE/PK constraints on columns referenced by a FK
        // Skip creating the unique constraint for the referenced columns if
        // they are already contained in the PK of the referenced entity
        if (
            columns.every((column) => column.isPrimary) ||
            !relation.isOneToOne
        ) {
            return { foreignKey, columns, uniqueConstraint: undefined }
        }

        const uniqueConstraint = new UniqueMetadata({
            entityMetadata: relation.entityMetadata,
            columns: foreignKey.columns,
            args: {
                name: this.connection.namingStrategy.relationConstraintName(
                    relation.entityMetadata.tableName,
                    foreignKey.columns.map((column) => column.databaseName),
                ),
                target: relation.entityMetadata.target,
            },
        })
        uniqueConstraint.build(this.connection.namingStrategy)

        return { foreignKey, columns, uniqueConstraint }
    }

    // -------------------------------------------------------------------------
    // Protected Methods
    // -------------------------------------------------------------------------

    /**
     * Collects referenced columns from the given join column args.
     */
    protected collectReferencedColumns(
        joinColumns: JoinColumnMetadataArgs[],
        relation: RelationMetadata,
    ): ColumnMetadata[] {
        const hasAnyReferencedColumnName = joinColumns.find(
            (joinColumnArgs) => !!joinColumnArgs.referencedColumnName,
        )
        const manyToOneWithoutJoinColumn =
            joinColumns.length === 0 && relation.isManyToOne
        const hasJoinColumnWithoutAnyReferencedColumnName =
            joinColumns.length > 0 && !hasAnyReferencedColumnName

        if (
            manyToOneWithoutJoinColumn ||
            hasJoinColumnWithoutAnyReferencedColumnName
        ) {
            // covers case3 and case1
            return relation.inverseEntityMetadata.primaryColumns
        } else {
            // cases with referenced columns defined
            return joinColumns.map((joinColumn) => {
                const referencedColumn =
                    relation.inverseEntityMetadata.ownColumns.find(
                        (column) =>
                            column.propertyName ===
                            joinColumn.referencedColumnName,
                    ) // todo: can we also search in relations?
                if (!referencedColumn)
                    throw new TypeORMError(
                        `Referenced column ${joinColumn.referencedColumnName} was not found in entity ${relation.inverseEntityMetadata.name}`,
                    )

                return referencedColumn
            })
        }
    }

    /**
     * Collects columns from the given join column args.
     */
    private collectColumns(
        joinColumns: JoinColumnMetadataArgs[],
        relation: RelationMetadata,
        referencedColumns: ColumnMetadata[],
    ): ColumnMetadata[] {
        return referencedColumns.map((referencedColumn) => {
            // in the case if relation has join column with only name set we need this check
            const joinColumnMetadataArg = joinColumns.find((joinColumn) => {
                return (
                    (!joinColumn.referencedColumnName ||
                        joinColumn.referencedColumnName ===
                            referencedColumn.propertyName) &&
                    !!joinColumn.name
                )
            })
            const joinColumnName = joinColumnMetadataArg
                ? joinColumnMetadataArg.name
                : this.connection.namingStrategy.joinColumnName(
                      relation.propertyName,
                      referencedColumn.propertyName,
                  )

            const relationalColumns = relation.embeddedMetadata
                ? relation.embeddedMetadata.columns
                : relation.entityMetadata.ownColumns
            let relationalColumn = relationalColumns.find(
                (column) =>
                    column.databaseNameWithoutPrefixes === joinColumnName,
            )
            if (!relationalColumn) {
                relationalColumn = new ColumnMetadata({
                    connection: this.connection,
                    entityMetadata: relation.entityMetadata,
                    embeddedMetadata: relation.embeddedMetadata,
                    args: {
                        target: "",
                        mode: "virtual",
                        propertyName: relation.propertyName,
                        options: {
                            name: joinColumnName,
                            type: referencedColumn.type,
                            length:
                                !referencedColumn.length &&
                                (DriverUtils.isMySQLFamily(
                                    this.connection.driver,
                                ) ||
                                    this.connection.driver.options.type ===
                                        "aurora-mysql") &&
                                // some versions of mariadb support the column type and should not try to provide the length property
                                this.connection.driver.normalizeType(
                                    referencedColumn,
                                ) !== "uuid" &&
                                (referencedColumn.generationStrategy ===
                                    "uuid" ||
                                    referencedColumn.type === "uuid")
                                    ? "36"
                                    : referencedColumn.length, // fix https://github.com/typeorm/typeorm/issues/3604
                            width: referencedColumn.width,
                            charset: referencedColumn.charset,
                            collation: referencedColumn.collation,
                            precision: referencedColumn.precision,
                            scale: referencedColumn.scale,
                            zerofill: referencedColumn.zerofill,
                            unsigned: referencedColumn.unsigned,
                            comment: referencedColumn.comment,
                            enum: referencedColumn.enum,
                            enumName: referencedColumn.enumName,
                            primary: relation.isPrimary,
                            nullable: relation.isNullable,
                        },
                    },
                })
                relation.entityMetadata.registerColumn(relationalColumn)
            }
            relationalColumn.referencedColumn = referencedColumn // its important to set it here because we need to set referenced column for user defined join column
            relationalColumn.type = referencedColumn.type // also since types of relational column and join column must be equal we override user defined column type
            relationalColumn.relationMetadata = relation
            relationalColumn.build(this.connection)
            return relationalColumn
        })
    }
}