import { Collection } from '../util'
import {QuerySafeValue, VectorEscapeValue} from './dialect/SQLDialect'

/**
 * A single query row, as an object.
 */
export type QueryRow = { [key: string]: any }

/**
 * A valid key on a model.
 */
export type ModelKey = string | number

/**
 * Collection of keys of a set of models.
 */
export type ModelKeys = ModelKey | ModelKey[] | Collection<ModelKey>

/**
 * Interface for the result of a query execution.
 */
export interface QueryResult {
    rows: Collection<QueryRow>,
    rowCount: number,
}

/**
 * SQL operator that is used to join two constraint clauses.
 */
export type ConstraintConnectionOperator = 'AND' | 'OR'  | 'AND NOT' | 'OR NOT'

/**
 * SQL operator that appears in a constraint clause.
 */
export type ConstraintOperator = '&' | '>' | '>=' | '<' | '<=' | '!=' | '<=>' | '%' | '|' | '!' | '~' | '=' | '^' | 'IN' | 'NOT IN' | 'LIKE' | 'BETWEEN' | 'NOT BETWEEN' | 'IS' | 'IS NOT';

/**
 * Interface for storing the various parts of a single SQL constraint.
 */
export interface ConstraintItem {
    field: string,
    operator: ConstraintOperator,
    operand: VectorEscapeValue<any>,
    preop: ConstraintConnectionOperator,
}

/**
 * Interface for storing a group of constraints connected by the given connection operator.
 */
export interface ConstraintGroup {
    items: Constraint[],
    preop: ConstraintConnectionOperator,
}

/**
 * Returns true if the given object is a valid ConstraintGroup.
 * @param what
 */
export function isConstraintGroup(what: unknown): what is ConstraintGroup {
    return typeof what === 'object' && Array.isArray((what as any).items) && (what as any).preop
}

/**
 * Returns true if the given object is a valid ConstraintItem
 * @param what
 */
export function isConstraintItem(what: unknown): what is ConstraintItem {
    return (
        typeof what === 'object'
        && (what as any).field
        && (what as any).operator
        && (what as any).operand
        && (what as any).preop
    )
}

/**
 * Type alias for something that can be either a single constraint or a group of them.
 */
export type Constraint = ConstraintItem | ConstraintGroup | QuerySafeValue

/**
 * Type alias for an item that refers to a field on a table.
 */
export type SpecifiedField = string | QuerySafeValue | { field: string | QuerySafeValue, alias: string }

/**
 * Type alias for an item that refers to a table in a database.
 */
export type QuerySource = string | QuerySafeValue | { table: string | QuerySafeValue, alias: string }

/**
 * Possible SQL order-by clause directions.
 */
export type OrderDirection = 'ASC' | 'DESC' | 'asc' | 'desc'

/**
 * Interface for storing the parts of a SQL order-by clause.
 */
export type OrderStatement = { field: string, direction: OrderDirection }

/**
 * Database column types.
 */
export enum FieldType {
    bigint = 'bigint',
    int8 = 'bigint',
    bigserial = 'bigserial',
    serial8 = 'bigserial',
    bit = 'bit',
    bitVarying = 'bit varying',
    varbit = 'bit varying',
    boolean = 'boolean',
    bool = 'boolean',
    box = 'box',
    bytea = 'bytea',
    character = 'character',
    char = 'character',
    characterVarying = 'character varying',
    varchar = 'character varying',
    cidr = 'cidr',
    circle = 'circle',
    date = 'date',
    doublePrecision = 'double precision',
    float8 = 'double precision',
    inet = 'inet',
    integer = 'integer',
    int = 'integer',
    int4 = 'integer',
    interval = 'interval',
    json = 'json',
    line = 'line',
    lseg = 'lseg',
    ltree = 'ltree',
    macaddr = 'macaddr',
    money = 'money',
    numeric = 'numeric',
    decimal = 'numeric',
    path = 'path',
    point = 'point',
    polygon = 'polygon',
    real = 'real',
    float4 = 'real',
    smallint = 'smallint',
    int2 = 'smallint',
    smallserial = 'smallserial',
    serial2 = 'smallserial',
    serial = 'serial',
    serial4 = 'serial',
    text = 'text',
    time = 'time',
    timestamp = 'timestamp',
    tsquery = 'tsquery',
    tsvector = 'tsvector',
    txidSnapshot = 'txidSnapshot',
    uuid = 'uuid',
    xml = 'xml',
    other = 'other',
}

/**
 * Given a FieldType, get the inverse (that is, the code-form name).
 * @example
 * ```ts
 * console.log(FieldType.varchar)  // => "character varying"
 * console.log(inverseFieldType(FieldType.varchar))  // => "varchar"
 * console.log(inverseFieldType('character varying'))  // => "varchar"
 * ```
 * @param type
 */
export function inverseFieldType(type: FieldType): string {
    return ({
        bigint: 'bigint',
        bigserial: 'bigserial',
        bit: 'bit',
        'bit varying': 'varbit',
        boolean: 'boolean',
        box: 'box',
        bytea: 'bytea',
        character: 'character',
        char: 'character',
        'character varying': 'varchar',
        cidr: 'cidr',
        circle: 'circle',
        date: 'date',
        'double precision': 'float8',
        inet: 'inet',
        integer: 'integer',
        interval: 'interval',
        json: 'json',
        line: 'line',
        lseg: 'lseg',
        ltree: 'ltree',
        macaddr: 'macaddr',
        money: 'money',
        numeric: 'numeric',
        path: 'path',
        point: 'point',
        polygon: 'polygon',
        real: 'real',
        smallint: 'smallint',
        smallserial: 'smallserial',
        serial: 'serial',
        text: 'text',
        time: 'time',
        timestamp: 'timestamp',
        tsquery: 'tsquery',
        tsvector: 'tsvector',
        txidSnapshot: 'txidSnapshot',
        uuid: 'uuid',
        xml: 'xml',
        other: 'other',
    })[type]
}