import { DecodeUtf8Stream, GatherStringStream } from "@yume-chan/stream-extra";

import { AdbCommandBase } from "../base.js";

import type {
    AdbSubprocessProtocol,
    AdbSubprocessProtocolConstructor,
} from "./protocols/index.js";
import {
    AdbSubprocessNoneProtocol,
    AdbSubprocessShellProtocol,
} from "./protocols/index.js";

export interface AdbSubprocessOptions {
    /**
     * A list of `AdbSubprocessProtocolConstructor`s to be used.
     *
     * Different `AdbSubprocessProtocol` has different capabilities, thus requires specific adaptations.
     * Check their documentations for details.
     *
     * The first protocol whose `isSupported` returns `true` will be used.
     * If no `AdbSubprocessProtocol` is supported, an error will be thrown.
     *
     * @default [AdbSubprocessShellProtocol, AdbSubprocessNoneProtocol]
     */
    protocols: AdbSubprocessProtocolConstructor[];
}

const DEFAULT_OPTIONS: AdbSubprocessOptions = {
    protocols: [AdbSubprocessShellProtocol, AdbSubprocessNoneProtocol],
};

export interface AdbSubprocessWaitResult {
    stdout: string;
    stderr: string;
    exitCode: number;
}

export class AdbSubprocess extends AdbCommandBase {
    private async createProtocol(
        mode: "pty" | "raw",
        command?: string | string[],
        options?: Partial<AdbSubprocessOptions>
    ): Promise<AdbSubprocessProtocol> {
        const { protocols } = { ...DEFAULT_OPTIONS, ...options };

        let Constructor: AdbSubprocessProtocolConstructor | undefined;
        for (const item of protocols) {
            // It's async so can't use `Array#find`
            if (await item.isSupported(this.adb)) {
                Constructor = item;
                break;
            }
        }

        if (!Constructor) {
            throw new Error("No specified protocol is supported by the device");
        }

        if (Array.isArray(command)) {
            command = command.join(" ");
        } else if (command === undefined) {
            // spawn the default shell
            command = "";
        }
        return await Constructor[mode](this.adb, command);
    }

    /**
     * Spawns an executable in PTY mode.
     *
     * Redirection mode is enough for most simple commands, but PTY mode is required for
     * commands that manipulate the terminal, such as `vi` and `less`.
     * @param command The command to run. If omitted, the default shell will be spawned.
     * @param options The options for creating the `AdbSubprocessProtocol`
     * @returns A new `AdbSubprocessProtocol` instance connecting to the spawned process.
     */
    public shell(
        command?: string | string[],
        options?: Partial<AdbSubprocessOptions>
    ): Promise<AdbSubprocessProtocol> {
        return this.createProtocol("pty", command, options);
    }

    /**
     * Spawns an executable and redirect the standard input/output stream.
     *
     * Redirection mode is enough for most simple commands, but PTY mode is required for
     * commands that manipulate the terminal, such as `vi` and `less`.
     * @param command The command to run, or an array of strings containing both command and args.
     * @param options The options for creating the `AdbSubprocessProtocol`
     * @returns A new `AdbSubprocessProtocol` instance connecting to the spawned process.
     */
    public spawn(
        command: string | string[],
        options?: Partial<AdbSubprocessOptions>
    ): Promise<AdbSubprocessProtocol> {
        return this.createProtocol("raw", command, options);
    }

    /**
     * Spawns a new process, waits until it exits, and returns the entire output.
     * @param command The command to run
     * @param options The options for creating the `AdbSubprocessProtocol`
     * @returns The entire output of the command
     */
    public async spawnAndWait(
        command: string | string[],
        options?: Partial<AdbSubprocessOptions>
    ): Promise<AdbSubprocessWaitResult> {
        const process = await this.spawn(command, options);

        const stdout = new GatherStringStream();
        const stderr = new GatherStringStream();

        const [, , exitCode] = await Promise.all([
            process.stdout.pipeThrough(new DecodeUtf8Stream()).pipeTo(stdout),
            process.stderr.pipeThrough(new DecodeUtf8Stream()).pipeTo(stderr),
            process.exit,
        ]);

        return {
            stdout: stdout.result,
            stderr: stderr.result,
            exitCode,
        };
    }

    /**
     * Spawns a new process, waits until it exits, and returns the entire output.
     * @param command The command to run
     * @returns The entire output of the command
     */
    public async spawnAndWaitLegacy(
        command: string | string[]
    ): Promise<string> {
        const { stdout } = await this.spawnAndWait(command, {
            protocols: [AdbSubprocessNoneProtocol],
        });
        return stdout;
    }
}