/**
 * Wraps SQL execution callbacks with request encoding and result decoding.
 *
 * `SqlSchema` is a small adapter between Effect Schema and SQL statements. Each
 * helper builds a function that accepts the decoded request type used by
 * application code, encodes it before calling `execute`, and decodes unknown
 * driver rows into the result schema. The helpers cover returning all rows, a
 * non-empty row list, the first row, an optional first row, or discarding the
 * SQL result for side-effect-only statements.
 *
 * @since 4.0.0
 */
import * as Arr from "../../Array.ts"
import * as Cause from "../../Cause.ts"
import * as Effect from "../../Effect.ts"
import type * as Option from "../../Option.ts"
import * as Schema from "../../Schema.ts"

/**
 * Builds a query function that encodes the request and decodes all result rows,
 * allowing an empty result set.
 *
 * **When to use**
 *
 * Use when you need to run a query that may return zero or more rows and
 * represent an empty result as an empty array.
 *
 * @see {@link findNonEmpty} for queries where an empty result is a failure
 *
 * @category constructors
 * @since 4.0.0
 */
export const findAll = <Req extends Schema.Constraint, Res extends Schema.Constraint, E, R>(
  options: {
    readonly Request: Req
    readonly Result: Res
    readonly execute: (request: Req["Encoded"]) => Effect.Effect<ReadonlyArray<unknown>, E, R>
  }
) => {
  const encodeRequest = Schema.encodeEffect(options.Request)
  const decode = Schema.decodeUnknownEffect(Schema.mutable(Schema.Array(options.Result)))
  return (
    request: Req["Type"]
  ): Effect.Effect<
    Array<Res["Type"]>,
    E | Schema.SchemaError,
    Req["EncodingServices"] | Res["DecodingServices"] | R
  > => Effect.flatMap(Effect.flatMap(encodeRequest(request), options.execute), decode)
}

/**
 * Builds a query function that encodes the request, decodes all result rows,
 * and fails with `NoSuchElementError` when the result set is empty.
 *
 * **When to use**
 *
 * Use when you need to run a query that must return at least one row and treat
 * an empty result as a failure.
 *
 * @see {@link findAll} for queries where an empty result should return an empty array
 *
 * @category constructors
 * @since 4.0.0
 */
export const findNonEmpty = <Req extends Schema.Constraint, Res extends Schema.Constraint, E, R>(
  options: {
    readonly Request: Req
    readonly Result: Res
    readonly execute: (request: Req["Encoded"]) => Effect.Effect<ReadonlyArray<unknown>, E, R>
  }
) => {
  const find = findAll(options)
  return (
    request: Req["Type"]
  ): Effect.Effect<
    Arr.NonEmptyArray<Res["Type"]>,
    E | Schema.SchemaError | Cause.NoSuchElementError,
    Req["EncodingServices"] | Res["DecodingServices"] | R
  > =>
    Effect.flatMap(find(request), (results) =>
      Arr.isArrayNonEmpty(results)
        ? Effect.succeed(results)
        : Effect.fail(new Cause.NoSuchElementError()))
}

const void_ = <Req extends Schema.Constraint, E, R>(
  options: {
    readonly Request: Req
    readonly execute: (request: Req["Encoded"]) => Effect.Effect<unknown, E, R>
  }
) => {
  const encode = Schema.encodeEffect(options.Request)
  return (request: Req["Type"]): Effect.Effect<void, E | Schema.SchemaError, R | Req["EncodingServices"]> =>
    Effect.asVoid(
      Effect.flatMap(encode(request), options.execute)
    )
}
export {
  /**
   * Runs a sql query with a request schema and discard the result.
   *
   * @category constructors
   * @since 4.0.0
   */
  void_ as void
}

/**
 * Builds a query function that encodes the request, decodes the first result
 * row, and fails with `NoSuchElementError` when no rows are returned.
 *
 * @category constructors
 * @since 4.0.0
 */
export const findOne = <Req extends Schema.Constraint, Res extends Schema.Constraint, E, R>(
  options: {
    readonly Request: Req
    readonly Result: Res
    readonly execute: (request: Req["Encoded"]) => Effect.Effect<ReadonlyArray<unknown>, E, R>
  }
) => {
  const encodeRequest = Schema.encodeEffect(options.Request)
  const decode = Schema.decodeUnknownEffect(options.Result)
  return (
    request: Req["Type"]
  ): Effect.Effect<
    Res["Type"],
    E | Schema.SchemaError | Cause.NoSuchElementError,
    R | Req["EncodingServices"] | Res["DecodingServices"]
  > =>
    Effect.flatMap(
      Effect.flatMap(encodeRequest(request), options.execute),
      (arr): Effect.Effect<
        Res["Type"],
        Schema.SchemaError | Cause.NoSuchElementError,
        Req["EncodingServices"] | Res["DecodingServices"]
      > => Arr.isReadonlyArrayNonEmpty(arr) ? decode(arr[0]) : Effect.fail(new Cause.NoSuchElementError())
    )
}

/**
 * Builds a query function that encodes the request, decodes the first result row
 * as `Option.some`, and returns `Option.none` when no rows are returned.
 *
 * @category constructors
 * @since 4.0.0
 */
export const findOneOption = <Req extends Schema.Constraint, Res extends Schema.Constraint, E, R>(
  options: {
    readonly Request: Req
    readonly Result: Res
    readonly execute: (request: Req["Encoded"]) => Effect.Effect<ReadonlyArray<unknown>, E, R>
  }
) => {
  const encodeRequest = Schema.encodeEffect(options.Request)
  const decode = Schema.decodeUnknownEffect(options.Result)
  return (
    request: Req["Type"]
  ): Effect.Effect<
    Option.Option<Res["Type"]>,
    E | Schema.SchemaError,
    R | Req["EncodingServices"] | Res["DecodingServices"]
  > =>
    Effect.flatMap(
      Effect.flatMap(encodeRequest(request), options.execute),
      (arr): Effect.Effect<
        Option.Option<Res["Type"]>,
        Schema.SchemaError,
        Req["EncodingServices"] | Res["DecodingServices"]
      > => Arr.isReadonlyArrayNonEmpty(arr) ? Effect.asSome(decode(arr[0])) : Effect.succeedNone
    )
}
