import { Config, Context, Effect, Layer } from "effect"

type ConfigMap = Record<string, Config.Config<unknown>>

/**

* The service shape inferred from an object of Effect `Config` definitions.

*/

export type Shape<Fields extends ConfigMap> = {

readonly [Key in keyof Fields]: Config.Success<Fields[Key]>

}

/**

* A Context service class with generated layers for config-backed services.

*/

export type ServiceClass<Self, Id extends string, Service> = Context.ServiceClass<Self, Id, Service> & {

/** Provide already-parsed config, useful in tests. */

readonly layer: (input: Service) => Layer.Layer<Self>

/** Parse config once from the active Effect ConfigProvider and provide the service. */

readonly defaultLayer: Layer.Layer<Self, Config.ConfigError>

}

/**

* Create a Context service whose implementation is derived from Effect `Config`.

*

* This keeps Effect `Config` as the source of truth for env names, defaults, and

* validation while generating a typed service plus convenient production/test

* layers.

*

* ```ts

* class ServerAuthConfig extends ConfigService.Service<ServerAuthConfig>()(

* "@opencode/ServerAuthConfig",

* {

* password: Config.string("OPENCODE_SERVER_PASSWORD").pipe(Config.option),

* username: Config.string("OPENCODE_SERVER_USERNAME").pipe(Config.withDefault("opencode")),

* },

* ) {}

*

* const live = ServerAuthConfig.defaultLayer

* const test = ServerAuthConfig.layer({ password: Option.some("secret"), username: "kit" })

* ```

*/

export const Service =

<Self>() =>

<const Id extends string, const Fields extends ConfigMap>(id: Id, fields: Fields) => {

class ConfigTag extends Context.Service<Self, Shape<Fields>>()(id) {

static layer(input: Shape<Fields>) {

return Layer.succeed(this, this.of(input))

}

static get defaultLayer() {

return Layer.effect(

this,

Config.all(fields)

.asEffect()

.pipe(

// oxlint-disable-next-line typescript-eslint/no-unsafe-type-assertion -- Config.all preserves the field shape, but its conditional return type also supports iterable inputs.

Effect.map((config) => this.of(config as Shape<Fields>)),

),

)

}

}

// oxlint-disable-next-line typescript-eslint/no-unsafe-type-assertion -- The generated class carries typed static helpers.

return ConfigTag as ServiceClass<Self, Id, Shape<Fields>>

}

export * as ConfigService from "./config-service"