#!/usr/bin/env python3
"""
Installer for YouTube Downloader dependencies.
Installs: yt-dlp, ffmpeg
Supports: Windows, macOS, Linux (Debian/Ubuntu, Fedora/RHEL, Arch)
"""

import os
import sys
import shutil
import subprocess
import platform


# ── Helpers ────────────────────────────────────────────────────────────────────

def run(cmd: list[str], check=True) -> subprocess.CompletedProcess:
    print(f"  → {' '.join(cmd)}")
    return subprocess.run(cmd, check=check)


def ok(msg: str):
    print(f"  ✅ {msg}")


def info(msg: str):
    print(f"  ℹ️  {msg}")


def warn(msg: str):
    print(f"  ⚠️  {msg}")


def fail(msg: str):
    print(f"  ❌ {msg}")
    sys.exit(1)


def section(title: str):
    print(f"\n{'─' * 50}")
    print(f"  {title}")
    print(f"{'─' * 50}")


# ── Platform detection ─────────────────────────────────────────────────────────

OS = platform.system()          # 'Windows', 'Darwin', 'Linux'
IS_WIN   = OS == "Windows"
IS_MAC   = OS == "Darwin"
IS_LINUX = OS == "Linux"


def linux_distro() -> str:
    """Return 'debian', 'fedora', 'arch', or 'unknown'."""
    if shutil.which("apt-get"):
        return "debian"
    if shutil.which("dnf") or shutil.which("yum"):
        return "fedora"
    if shutil.which("pacman"):
        return "arch"
    return "unknown"


# ── Python / pip check ─────────────────────────────────────────────────────────

def check_python():
    section("Checking Python")
    major, minor = sys.version_info[:2]
    print(f"  Python {major}.{minor} detected")
    if major < 3 or (major == 3 and minor < 8):
        fail("Python 3.8+ is required. Please upgrade and re-run this script.")
    ok("Python version is compatible")


def ensure_pip():
    section("Checking pip")
    try:
        import pip  # noqa: F401
        ok("pip is available")
    except ImportError:
        info("pip not found — installing via ensurepip...")
        run([sys.executable, "-m", "ensurepip", "--upgrade"])
        ok("pip installed")

    # Always upgrade pip to avoid resolver issues
    run([sys.executable, "-m", "pip", "install", "--upgrade", "pip"])
    ok("pip is up to date")


# ── yt-dlp ─────────────────────────────────────────────────────────────────────

def install_ytdlp():
    section("Installing yt-dlp")
    run([sys.executable, "-m", "pip", "install", "--upgrade", "yt-dlp"])
    ok("yt-dlp installed/updated")


# ── ffmpeg ─────────────────────────────────────────────────────────────────────

def ffmpeg_already_installed() -> bool:
    if shutil.which("ffmpeg"):
        result = subprocess.run(
            ["ffmpeg", "-version"], capture_output=True, text=True, check=False
        )
        version_line = result.stdout.splitlines()[0] if result.stdout else "unknown"
        info(f"ffmpeg already installed: {version_line}")
        return True
    return False


def install_ffmpeg_windows():
    """
    On Windows, download the pre-built ffmpeg binary via winget or chocolatey.
    Falls back to manual instructions if neither is available.
    """
    if shutil.which("winget"):
        info("Using winget to install ffmpeg...")
        run(["winget", "install", "--id", "Gyan.FFmpeg", "-e", "--silent"])
    elif shutil.which("choco"):
        info("Using Chocolatey to install ffmpeg...")
        run(["choco", "install", "ffmpeg", "-y"])
    elif shutil.which("scoop"):
        info("Using Scoop to install ffmpeg...")
        run(["scoop", "install", "ffmpeg"])
    else:
        warn("No package manager found (winget / choco / scoop).")
        print("""
  Please install ffmpeg manually:
    1. Go to https://www.gyan.dev/ffmpeg/builds/
    2. Download the latest 'release essentials' zip
    3. Extract it and add the 'bin' folder to your PATH
        """)
        return
    ok("ffmpeg installed")


def install_ffmpeg_mac():
    if shutil.which("brew"):
        info("Using Homebrew to install ffmpeg...")
        run(["brew", "install", "ffmpeg"])
    elif shutil.which("port"):
        info("Using MacPorts to install ffmpeg...")
        run(["sudo", "port", "install", "ffmpeg"])
    else:
        warn("Homebrew not found. Installing Homebrew first...")
        install_cmd = (
            '/bin/bash -c "$(curl -fsSL '
            'https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"'
        )
        subprocess.run(install_cmd, shell=True, check=True)
        run(["brew", "install", "ffmpeg"])
    ok("ffmpeg installed")


def install_ffmpeg_linux():
    distro = linux_distro()

    if distro == "debian":
        info("Using apt-get (Debian/Ubuntu)...")
        run(["sudo", "apt-get", "update", "-qq"])
        run(["sudo", "apt-get", "install", "-y", "ffmpeg"])

    elif distro == "fedora":
        info("Using dnf (Fedora/RHEL)...")
        # ffmpeg lives in RPM Fusion on Fedora
        run(["sudo", "dnf", "install", "-y",
             "https://download1.rpmfusion.org/free/fedora/"
             "rpmfusion-free-release-$(rpm -E %fedora).noarch.rpm"], check=False)
        run(["sudo", "dnf", "install", "-y", "ffmpeg"])

    elif distro == "arch":
        info("Using pacman (Arch Linux)...")
        run(["sudo", "pacman", "-Sy", "--noconfirm", "ffmpeg"])

    else:
        warn("Unrecognised Linux distro — cannot auto-install ffmpeg.")
        print("""
  Please install ffmpeg with your distro's package manager, e.g.:
    sudo apt-get install ffmpeg        # Debian / Ubuntu
    sudo dnf install ffmpeg            # Fedora
    sudo pacman -S ffmpeg              # Arch
        """)
        return

    ok("ffmpeg installed")


def install_ffmpeg():
    section("Installing ffmpeg")

    if ffmpeg_already_installed():
        ok("Skipping — ffmpeg is already installed")
        return

    if IS_WIN:
        install_ffmpeg_windows()
    elif IS_MAC:
        install_ffmpeg_mac()
    elif IS_LINUX:
        install_ffmpeg_linux()
    else:
        warn(f"Unsupported OS: {OS}")


# ── Final verification ─────────────────────────────────────────────────────────

def verify():
    section("Verification")
    all_good = True

    # yt-dlp
    try:
        import yt_dlp
        ok(f"yt-dlp {yt_dlp.version.__version__}")
    except ImportError:
        fail("yt-dlp import failed after installation!")
        all_good = False

    # ffmpeg
    if shutil.which("ffmpeg"):
        result = subprocess.run(
            ["ffmpeg", "-version"], capture_output=True, text=True, check=False
        )
        version_line = result.stdout.splitlines()[0] if result.stdout else "unknown version"
        ok(f"ffmpeg — {version_line}")
    else:
        warn("ffmpeg not found in PATH. High-quality merging may not work.")
        warn("You can still download videos but 1080p/4K may be unavailable.")
        all_good = False

    return all_good


# ── Main ───────────────────────────────────────────────────────────────────────

def main():
    print("\n" + "=" * 50)
    print("   YouTube Downloader — Dependency Installer")
    print("=" * 50)
    print(f"  OS      : {OS} ({platform.machine()})")
    print(f"  Python  : {sys.version.split()[0]}")

    check_python()
    ensure_pip()
    install_ytdlp()
    install_ffmpeg()

    all_good = verify()

    print("\n" + "=" * 50)
    if all_good:
        print("  🎉 All dependencies installed successfully!")
        print("  Run  python yt_downloader.py  to start downloading.")
    else:
        print("  ⚠️  Setup finished with warnings (see above).")
    print("=" * 50 + "\n")


if __name__ == "__main__":
    main()