import {
  DesktopServerExposureModeSchema,
  DesktopUpdateChannelSchema,
  type DesktopServerExposureMode,
  type DesktopUpdateChannel,
} from "@t3tools/contracts";
import { fromLenientJson } from "@t3tools/shared/schemaJson";
import * as Context from "effect/Context";
import * as Crypto from "effect/Crypto";
import * as Effect from "effect/Effect";
import * as FileSystem from "effect/FileSystem";
import * as Layer from "effect/Layer";
import * as Option from "effect/Option";
import * as Path from "effect/Path";
import * as Schema from "effect/Schema";
import * as SynchronizedRef from "effect/SynchronizedRef";

import * as DesktopEnvironment from "../app/DesktopEnvironment.ts";
import { resolveDefaultDesktopUpdateChannel } from "../updates/updateChannels.ts";

export interface DesktopSettings {
  readonly serverExposureMode: DesktopServerExposureMode;
  readonly tailscaleServeEnabled: boolean;
  readonly tailscaleServePort: number;
  readonly updateChannel: DesktopUpdateChannel;
  readonly updateChannelConfiguredByUser: boolean;
}

export interface DesktopSettingsChange {
  readonly settings: DesktopSettings;
  readonly changed: boolean;
}

export const DEFAULT_TAILSCALE_SERVE_PORT = 443;

export const DEFAULT_DESKTOP_SETTINGS: DesktopSettings = {
  serverExposureMode: "local-only",
  tailscaleServeEnabled: false,
  tailscaleServePort: DEFAULT_TAILSCALE_SERVE_PORT,
  updateChannel: "latest",
  updateChannelConfiguredByUser: false,
};

const DesktopSettingsDocument = Schema.Struct({
  serverExposureMode: Schema.optionalKey(DesktopServerExposureModeSchema),
  tailscaleServeEnabled: Schema.optionalKey(Schema.Boolean),
  tailscaleServePort: Schema.optionalKey(Schema.Number),
  updateChannel: Schema.optionalKey(DesktopUpdateChannelSchema),
  updateChannelConfiguredByUser: Schema.optionalKey(Schema.Boolean),
});

type DesktopSettingsDocument = typeof DesktopSettingsDocument.Type;
type Mutable<T> = { -readonly [K in keyof T]: T[K] };

const DesktopSettingsJson = fromLenientJson(DesktopSettingsDocument);
const decodeDesktopSettingsJson = Schema.decodeEffect(DesktopSettingsJson);
const encodeDesktopSettingsJson = Schema.encodeEffect(DesktopSettingsJson);

const settingsChange = (settings: DesktopSettings, changed: boolean): DesktopSettingsChange => ({
  settings,
  changed,
});

const DesktopSettingsWriteOperation = Schema.Literals([
  "create-temporary-file-name",
  "encode-document",
  "create-directory",
  "write-temporary-file",
  "replace-settings-file",
]);
type DesktopSettingsWriteOperation = typeof DesktopSettingsWriteOperation.Type;

export class DesktopSettingsWriteError extends Schema.TaggedErrorClass<DesktopSettingsWriteError>()(
  "DesktopSettingsWriteError",
  {
    operation: DesktopSettingsWriteOperation,
    path: Schema.String,
    cause: Schema.Defect(),
  },
) {
  override get message(): string {
    return `Desktop settings write failed during ${this.operation} at ${this.path}.`;
  }
}

const writeError = (
  operation: DesktopSettingsWriteOperation,
  path: string,
  cause: unknown,
): DesktopSettingsWriteError => new DesktopSettingsWriteError({ operation, path, cause });

export class DesktopAppSettings extends Context.Service<
  DesktopAppSettings,
  {
    readonly load: Effect.Effect<DesktopSettings>;
    readonly get: Effect.Effect<DesktopSettings>;
    readonly setServerExposureMode: (
      mode: DesktopServerExposureMode,
    ) => Effect.Effect<DesktopSettingsChange, DesktopSettingsWriteError>;
    readonly setTailscaleServe: (input: {
      readonly enabled: boolean;
      readonly port: Option.Option<number>;
    }) => Effect.Effect<DesktopSettingsChange, DesktopSettingsWriteError>;
    readonly setUpdateChannel: (
      channel: DesktopUpdateChannel,
    ) => Effect.Effect<DesktopSettingsChange, DesktopSettingsWriteError>;
  }
>()("@t3tools/desktop/settings/DesktopAppSettings") {}

export function resolveDefaultDesktopSettings(appVersion: string): DesktopSettings {
  return {
    ...DEFAULT_DESKTOP_SETTINGS,
    updateChannel: resolveDefaultDesktopUpdateChannel(appVersion),
  };
}

function normalizeTailscaleServePort(value: unknown): number {
  return typeof value === "number" && Number.isInteger(value) && value >= 1 && value <= 65_535
    ? value
    : DEFAULT_TAILSCALE_SERVE_PORT;
}

function normalizeDesktopSettingsDocument(
  parsed: DesktopSettingsDocument,
  appVersion: string,
): DesktopSettings {
  const defaultSettings = resolveDefaultDesktopSettings(appVersion);
  const parsedUpdateChannel = Option.fromNullishOr(parsed.updateChannel);
  const isLegacySettings = parsed.updateChannelConfiguredByUser === undefined;
  const updateChannelConfiguredByUser =
    parsed.updateChannelConfiguredByUser === true ||
    (isLegacySettings && Option.contains(parsedUpdateChannel, "nightly"));

  return {
    serverExposureMode:
      parsed.serverExposureMode === "network-accessible" ? "network-accessible" : "local-only",
    tailscaleServeEnabled: parsed.tailscaleServeEnabled === true,
    tailscaleServePort: normalizeTailscaleServePort(parsed.tailscaleServePort),
    updateChannel: updateChannelConfiguredByUser
      ? Option.getOrElse(parsedUpdateChannel, () => defaultSettings.updateChannel)
      : defaultSettings.updateChannel,
    updateChannelConfiguredByUser,
  };
}

function toDesktopSettingsDocument(
  settings: DesktopSettings,
  defaults: DesktopSettings,
): DesktopSettingsDocument {
  const document: Mutable<DesktopSettingsDocument> = {};

  if (settings.serverExposureMode !== defaults.serverExposureMode) {
    document.serverExposureMode = settings.serverExposureMode;
  }
  if (settings.tailscaleServeEnabled !== defaults.tailscaleServeEnabled) {
    document.tailscaleServeEnabled = settings.tailscaleServeEnabled;
  }
  if (settings.tailscaleServePort !== defaults.tailscaleServePort) {
    document.tailscaleServePort = settings.tailscaleServePort;
  }
  if (settings.updateChannel !== defaults.updateChannel) {
    document.updateChannel = settings.updateChannel;
  }
  if (settings.updateChannelConfiguredByUser !== defaults.updateChannelConfiguredByUser) {
    document.updateChannelConfiguredByUser = settings.updateChannelConfiguredByUser;
  }

  return document;
}

function setServerExposureMode(
  settings: DesktopSettings,
  requestedMode: DesktopServerExposureMode,
): DesktopSettings {
  return settings.serverExposureMode === requestedMode
    ? settings
    : {
        ...settings,
        serverExposureMode: requestedMode,
      };
}

function setTailscaleServe(
  settings: DesktopSettings,
  input: { readonly enabled: boolean; readonly port: Option.Option<number> },
): DesktopSettings {
  const port = Option.match(input.port, {
    onNone: () => settings.tailscaleServePort,
    onSome: normalizeTailscaleServePort,
  });
  return settings.tailscaleServeEnabled === input.enabled && settings.tailscaleServePort === port
    ? settings
    : {
        ...settings,
        tailscaleServeEnabled: input.enabled,
        tailscaleServePort: port,
      };
}

function setUpdateChannel(
  settings: DesktopSettings,
  requestedChannel: DesktopUpdateChannel,
): DesktopSettings {
  return settings.updateChannel === requestedChannel
    ? settings
    : {
        ...settings,
        updateChannel: requestedChannel,
        updateChannelConfiguredByUser: true,
      };
}

function readSettings(
  fileSystem: FileSystem.FileSystem,
  settingsPath: string,
  appVersion: string,
): Effect.Effect<DesktopSettings> {
  const defaultSettings = resolveDefaultDesktopSettings(appVersion);

  return fileSystem.readFileString(settingsPath).pipe(
    Effect.option,
    Effect.flatMap(
      Option.match({
        onNone: () => Effect.succeed(defaultSettings),
        onSome: (raw) =>
          decodeDesktopSettingsJson(raw).pipe(
            Effect.map((parsed) => normalizeDesktopSettingsDocument(parsed, appVersion)),
            Effect.orElseSucceed(() => defaultSettings),
          ),
      }),
    ),
  );
}

const writeSettings = Effect.fn("desktop.settings.writeSettings")(function* (input: {
  readonly fileSystem: FileSystem.FileSystem;
  readonly path: Path.Path;
  readonly settingsPath: string;
  readonly settings: DesktopSettings;
  readonly defaultSettings: DesktopSettings;
  readonly suffix: string;
}): Effect.fn.Return<void, DesktopSettingsWriteError> {
  const directory = input.path.dirname(input.settingsPath);
  const tempPath = `${input.settingsPath}.${process.pid}.${input.suffix}.tmp`;
  const encoded = yield* encodeDesktopSettingsJson(
    toDesktopSettingsDocument(input.settings, input.defaultSettings),
  ).pipe(Effect.mapError((cause) => writeError("encode-document", input.settingsPath, cause)));
  yield* input.fileSystem
    .makeDirectory(directory, { recursive: true })
    .pipe(Effect.mapError((cause) => writeError("create-directory", directory, cause)));
  yield* input.fileSystem
    .writeFileString(tempPath, `${encoded}\n`)
    .pipe(Effect.mapError((cause) => writeError("write-temporary-file", tempPath, cause)));
  yield* input.fileSystem
    .rename(tempPath, input.settingsPath)
    .pipe(
      Effect.mapError((cause) => writeError("replace-settings-file", input.settingsPath, cause)),
    );
});

export const make = Effect.gen(function* () {
  const environment = yield* DesktopEnvironment.DesktopEnvironment;
  const fileSystem = yield* FileSystem.FileSystem;
  const path = yield* Path.Path;
  const crypto = yield* Crypto.Crypto;
  const settingsRef = yield* SynchronizedRef.make(environment.defaultDesktopSettings);

  const persist = (
    update: (settings: DesktopSettings) => DesktopSettings,
  ): Effect.Effect<DesktopSettingsChange, DesktopSettingsWriteError> =>
    SynchronizedRef.modifyEffect(settingsRef, (settings) => {
      const nextSettings = update(settings);
      if (nextSettings === settings) {
        return Effect.succeed([settingsChange(settings, false), settings] as const);
      }

      return crypto.randomUUIDv4.pipe(
        Effect.map((uuid) => uuid.replace(/-/g, "")),
        Effect.mapError((cause) =>
          writeError("create-temporary-file-name", environment.desktopSettingsPath, cause),
        ),
        Effect.flatMap((suffix) =>
          writeSettings({
            fileSystem,
            path,
            settingsPath: environment.desktopSettingsPath,
            settings: nextSettings,
            defaultSettings: environment.defaultDesktopSettings,
            suffix,
          }),
        ),
        Effect.as([settingsChange(nextSettings, true), nextSettings] as const),
      );
    });

  return DesktopAppSettings.of({
    get: SynchronizedRef.get(settingsRef),
    load: Effect.gen(function* () {
      const settings = yield* readSettings(
        fileSystem,
        environment.desktopSettingsPath,
        environment.appVersion,
      );
      return yield* SynchronizedRef.setAndGet(settingsRef, settings);
    }).pipe(Effect.withSpan("desktop.settings.load")),
    setServerExposureMode: (mode) =>
      persist((settings) => setServerExposureMode(settings, mode)).pipe(
        Effect.withSpan("desktop.settings.setServerExposureMode", { attributes: { mode } }),
      ),
    setTailscaleServe: (input) =>
      persist((settings) => setTailscaleServe(settings, input)).pipe(
        Effect.withSpan("desktop.settings.setTailscaleServe", { attributes: input }),
      ),
    setUpdateChannel: (channel) =>
      persist((settings) => setUpdateChannel(settings, channel)).pipe(
        Effect.withSpan("desktop.settings.setUpdateChannel", { attributes: { channel } }),
      ),
  });
});

export const layer = Layer.effect(DesktopAppSettings, make);

export const layerTest = (initialSettings: DesktopSettings = DEFAULT_DESKTOP_SETTINGS) =>
  Layer.effect(
    DesktopAppSettings,
    Effect.gen(function* () {
      const settingsRef = yield* SynchronizedRef.make(initialSettings);
      const update = (f: (settings: DesktopSettings) => DesktopSettings) =>
        SynchronizedRef.modify(settingsRef, (settings) => {
          const nextSettings = f(settings);
          return [
            {
              settings: nextSettings,
              changed: nextSettings !== settings,
            },
            nextSettings,
          ] as const;
        });

      return DesktopAppSettings.of({
        get: SynchronizedRef.get(settingsRef),
        load: SynchronizedRef.get(settingsRef),
        setServerExposureMode: (mode) =>
          update((settings) => setServerExposureMode(settings, mode)),
        setTailscaleServe: (input) => update((settings) => setTailscaleServe(settings, input)),
        setUpdateChannel: (channel) => update((settings) => setUpdateChannel(settings, channel)),
      });
    }),
  );