import { EntityMetadata } from "./EntityMetadata"
import { IndexMetadataArgs } from "../metadata-args/IndexMetadataArgs"
import { NamingStrategyInterface } from "../naming-strategy/NamingStrategyInterface"
import { ColumnMetadata } from "./ColumnMetadata"
import { EmbeddedMetadata } from "./EmbeddedMetadata"
import { TypeORMError } from "../error"

/**
 * Index metadata contains all information about table's index.
 */
export class IndexMetadata {
    // ---------------------------------------------------------------------
    // Public Properties
    // ---------------------------------------------------------------------

    /**
     * Entity metadata of the class to which this index is applied.
     */
    entityMetadata: EntityMetadata

    /**
     * Embedded metadata if this index was applied on embedded.
     */
    embeddedMetadata?: EmbeddedMetadata

    /**
     * Indicates if this index must be unique.
     */
    isUnique: boolean = false

    /**
     * The SPATIAL modifier indexes the entire column and does not allow indexed columns to contain NULL values.
     * Works only in MySQL.
     */
    isSpatial: boolean = false

    /**
     * The FULLTEXT modifier indexes the entire column and does not allow prefixing.
     * Works only in MySQL.
     */
    isFulltext: boolean = false

    /**
     * NULL_FILTERED indexes are particularly useful for indexing sparse columns, where most rows contain a NULL value.
     * In these cases, the NULL_FILTERED index can be considerably smaller and more efficient to maintain than
     * a normal index that includes NULL values.
     *
     * Works only in Spanner.
     */
    isNullFiltered: boolean = false

    /**
     * Fulltext parser.
     * Works only in MySQL.
     */
    parser?: string

    /**
     * Indicates if this index must synchronize with database index.
     */
    synchronize: boolean = true

    /**
     * If true, the index only references documents with the specified field.
     * These indexes use less space but behave differently in some situations (particularly sorts).
     * This option is only supported for mongodb database.
     */
    isSparse?: boolean

    /**
     * Builds the index in the background so that building an index an does not block other database activities.
     * This option is only supported for mongodb database.
     */
    isBackground?: boolean

    /**
     * Specifies a time to live, in seconds.
     * This option is only supported for mongodb database.
     */
    expireAfterSeconds?: number

    /**
     * Target class to which metadata is applied.
     */
    target?: Function | string

    /**
     * Indexed columns.
     */
    columns: ColumnMetadata[] = []

    /**
     * User specified index name.
     */
    givenName?: string

    /**
     * User specified column names.
     */
    givenColumnNames?:
        | ((object?: any) => any[] | { [key: string]: number })
        | string[]

    /**
     * Final index name.
     * If index name was given by a user then it stores normalized (by naming strategy) givenName.
     * If index name was not given then its generated.
     */
    name: string

    /**
     * Index filter condition.
     */
    where?: string

    /**
     * Map of column names with order set.
     * Used only by MongoDB driver.
     */
    columnNamesWithOrderingMap: { [key: string]: number } = {}

    // ---------------------------------------------------------------------
    // Constructor
    // ---------------------------------------------------------------------

    constructor(options: {
        entityMetadata: EntityMetadata
        embeddedMetadata?: EmbeddedMetadata
        columns?: ColumnMetadata[]
        args?: IndexMetadataArgs
    }) {
        this.entityMetadata = options.entityMetadata
        this.embeddedMetadata = options.embeddedMetadata
        if (options.columns) this.columns = options.columns

        if (options.args) {
            this.target = options.args.target
            if (
                options.args.synchronize !== null &&
                options.args.synchronize !== undefined
            )
                this.synchronize = options.args.synchronize
            this.isUnique = !!options.args.unique
            this.isSpatial = !!options.args.spatial
            this.isFulltext = !!options.args.fulltext
            this.isNullFiltered = !!options.args.nullFiltered
            this.parser = options.args.parser
            this.where = options.args.where
            this.isSparse = options.args.sparse
            this.isBackground = options.args.background
            this.expireAfterSeconds = options.args.expireAfterSeconds
            this.givenName = options.args.name
            this.givenColumnNames = options.args.columns
        }
    }

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

    /**
     * Builds some depend index properties.
     * Must be called after all entity metadata's properties map, columns and relations are built.
     */
    build(namingStrategy: NamingStrategyInterface): this {
        if (this.synchronize === false) {
            this.name = this.givenName!
            return this
        }

        const map: { [key: string]: number } = {}

        // if columns already an array of string then simply return it
        if (this.givenColumnNames) {
            let columnPropertyPaths: string[] = []
            if (Array.isArray(this.givenColumnNames)) {
                columnPropertyPaths = this.givenColumnNames.map(
                    (columnName) => {
                        if (this.embeddedMetadata)
                            return (
                                this.embeddedMetadata.propertyPath +
                                "." +
                                columnName
                            )

                        return columnName.trim()
                    },
                )
                columnPropertyPaths.forEach(
                    (propertyPath) => (map[propertyPath] = 1),
                )
            } else {
                // todo: indices in embeds are not implemented in this syntax. deprecate this syntax?
                // if columns is a function that returns array of field names then execute it and get columns names from it
                const columnsFnResult = this.givenColumnNames(
                    this.entityMetadata.propertiesMap,
                )
                if (Array.isArray(columnsFnResult)) {
                    columnPropertyPaths = columnsFnResult.map((i: any) =>
                        String(i),
                    )
                    columnPropertyPaths.forEach((name) => (map[name] = 1))
                } else {
                    columnPropertyPaths = Object.keys(columnsFnResult).map(
                        (i: any) => String(i),
                    )
                    Object.keys(columnsFnResult).forEach(
                        (columnName) =>
                            (map[columnName] = columnsFnResult[columnName]),
                    )
                }
            }

            this.columns = columnPropertyPaths
                .map((propertyPath) => {
                    const columnWithSameName = this.entityMetadata.columns.find(
                        (column) => column.propertyPath === propertyPath,
                    )
                    if (columnWithSameName) {
                        return [columnWithSameName]
                    }
                    const relationWithSameName =
                        this.entityMetadata.relations.find(
                            (relation) =>
                                relation.isWithJoinColumn &&
                                relation.propertyName === propertyPath,
                        )
                    if (relationWithSameName) {
                        return relationWithSameName.joinColumns
                    }
                    const indexName = this.givenName
                        ? '"' + this.givenName + '" '
                        : ""
                    const entityName = this.entityMetadata.targetName
                    throw new TypeORMError(
                        `Index ${indexName}contains column that is missing in the entity (${entityName}): ` +
                            propertyPath,
                    )
                })
                .reduce((a, b) => a.concat(b))
        }

        this.columnNamesWithOrderingMap = Object.keys(map).reduce(
            (updatedMap, key) => {
                const column = this.entityMetadata.columns.find(
                    (column) => column.propertyPath === key,
                )
                if (column) updatedMap[column.databasePath] = map[key]

                return updatedMap
            },
            {} as { [key: string]: number },
        )

        this.name = this.givenName
            ? this.givenName
            : namingStrategy.indexName(
                  this.entityMetadata.tableName,
                  this.columns.map((column) => column.databaseName),
                  this.where,
              )
        return this
    }
}