#!/bin/bash
# Amethyst Mod Manager installer
# Downloads latest AppImage, icon, and creates a .desktop entry
#
# Portable across Linux distros: uses XDG paths (~/.local/share) and
# creates ~/Applications if missing. Requires curl or wget.

set -e

ALLOW_PRERELEASE=0
CUSTOM_DEST=""
while [ $# -gt 0 ]; do
    case "$1" in
        --prerelease) ALLOW_PRERELEASE=1 ;;
        --dest) CUSTOM_DEST="$2"; shift ;;
    esac
    shift
done

REPO="ChrisDKN/Amethyst-Mod-Manager"
BASE_URL="https://raw.githubusercontent.com/${REPO}/main"
ICON_URL="${BASE_URL}/src/icons/title-bar.png"
RELEASES_API_URL="https://api.github.com/repos/${REPO}/releases/latest"
RELEASES_LIST_API_URL="https://api.github.com/repos/${REPO}/releases?per_page=20"

# ~/Applications: not standard on all distros; we create it (common on Steam Deck)
APPLICATIONS_DIR="${HOME}/Applications"
# XDG Base Dir: standard on all desktop Linux (Ubuntu, Fedora, Arch, etc.)
XDG_DATA="${XDG_DATA_HOME:-$HOME/.local/share}"
ICONS_DIR="${XDG_DATA}/icons"
APPLICATIONS_DESKTOP_DIR="${XDG_DATA}/applications"

# Local name is fixed so .desktop entry and updates overwrite the same file
APPIMAGE_NAME="AmethystModManager-x86_64.AppImage"
ICON_NAME="title-bar.png"
DESKTOP_NAME="amethyst-mod-manager.desktop"

echo "Amethyst Mod Manager installer"
echo "=============================="

# Discover latest AppImage from GitHub Releases
echo "Checking for latest version..."
if [ "$ALLOW_PRERELEASE" = "1" ]; then
    URL="$RELEASES_LIST_API_URL"
else
    URL="$RELEASES_API_URL"
fi
# Honor GITHUB_TOKEN (or GH_TOKEN) to lift the 60 req/hour unauthenticated
# rate limit - useful on shared IPs and in CI.
GH_AUTH_TOKEN="${GITHUB_TOKEN:-${GH_TOKEN:-}}"
if command -v curl &>/dev/null; then
    if [ -n "$GH_AUTH_TOKEN" ]; then
        JSON="$(curl -sL -H "Authorization: Bearer $GH_AUTH_TOKEN" "$URL")"
    else
        JSON="$(curl -sL "$URL")"
    fi
else
    if [ -n "$GH_AUTH_TOKEN" ]; then
        JSON="$(wget -qO- --header="Authorization: Bearer $GH_AUTH_TOKEN" "$URL")"
    else
        JSON="$(wget -qO- "$URL")"
    fi
fi

# Distinguish a GitHub API error (rate limit, network, private repo) from a
# real missing asset - otherwise the check below blames a missing AppImage.
if echo "$JSON" | grep -q '"message" *: *"API rate limit exceeded'; then
    echo "Error: GitHub API rate limit exceeded for your IP." >&2
    echo "Wait ~1 hour, or set GITHUB_TOKEN=<your token> and retry." >&2
    exit 1
fi

# Both paths parse with the same grep/sed pipeline. On /releases/latest the
# response is a single object; on /releases?per_page=N it's an array sorted
# newest-first by published_at - so head -1 picks the newest release in both
# cases. We deliberately avoid python3 here: the installer is invoked by the
# running AppImage, whose env can leave the bundled python's sys.path pointing
# at a now-unmounted FUSE path, causing import failures.
LATEST_VERSION="$(echo "$JSON" | grep -o '"tag_name" *: *"[^"]*"' | sed 's/.*: *"v\{0,1\}\([^"]*\)"/\1/' | head -1)"
APPIMAGE_URL="$(echo "$JSON" | grep -o '"browser_download_url" *: *"[^"]*\.AppImage"' | sed 's/.*: *"\([^"]*\)"/\1/' | head -1)"
if [ -z "$APPIMAGE_URL" ]; then
    echo "Error: Could not find an AppImage asset in the latest release." >&2
    exit 1
fi
echo "Latest version: ${LATEST_VERSION}"
echo ""

# --dest = update-in-place mode: the caller (the running app) passed the path
# of the AppImage it was launched from, which may live wherever the user's
# AppImage manager (GearLever, AppImageLauncher, ...) put it - GH#361. In that
# mode we ONLY replace that file; the manager owns the icon and .desktop
# entry, and creating our own here is exactly what duplicated the app-drawer
# entries. Without --dest, do the classic full install to ~/Applications.
if [ -n "$CUSTOM_DEST" ] && [ "$CUSTOM_DEST" != "$APPLICATIONS_DIR/$APPIMAGE_NAME" ]; then
    APPIMAGE_DEST="$CUSTOM_DEST"
    MANAGE_DESKTOP=0
else
    APPIMAGE_DEST="$APPLICATIONS_DIR/$APPIMAGE_NAME"
    MANAGE_DESKTOP=1
fi

# Create directories if they don't exist
mkdir -p "$(dirname "$APPIMAGE_DEST")"
if [ "$MANAGE_DESKTOP" = "1" ]; then
    mkdir -p "$ICONS_DIR"
    mkdir -p "$APPLICATIONS_DESKTOP_DIR"
fi

# Download AppImage to a sibling temp file, then atomically rename it into
# place. Writing directly to the destination fails with ETXTBSY ("Text file
# busy") when the currently-running AppImage is still being unmounted by the
# kernel. rename(2) on the same filesystem only swaps the directory entry -
# the running process keeps its open inode, so there is no conflict.
APPIMAGE_TMP="$APPIMAGE_DEST.new"
echo "Downloading AppImage..."
if command -v curl &>/dev/null; then
    curl --fail --show-error --location -o "$APPIMAGE_TMP" "$APPIMAGE_URL"
elif command -v wget &>/dev/null; then
    wget -O "$APPIMAGE_TMP" "$APPIMAGE_URL"
else
    echo "Error: neither curl nor wget found. Please install one of them." >&2
    exit 1
fi

chmod +x "$APPIMAGE_TMP"
mv -f "$APPIMAGE_TMP" "$APPIMAGE_DEST"
echo "AppImage installed to $APPIMAGE_DEST (executable)."

if [ "$MANAGE_DESKTOP" = "0" ]; then
    echo ""
    echo "Update complete. Icon and menu entry are managed by your AppImage manager."
    exit 0
fi

# Download icon
echo "Downloading icon..."
if command -v curl &>/dev/null; then
    curl --fail --show-error --location -o "$ICONS_DIR/$ICON_NAME" "$ICON_URL"
elif command -v wget &>/dev/null; then
    wget -O "$ICONS_DIR/$ICON_NAME" "$ICON_URL"
fi
echo "Icon installed to $ICONS_DIR/$ICON_NAME."

# Create .desktop entry
DESKTOP_FILE="$APPLICATIONS_DESKTOP_DIR/$DESKTOP_NAME"
cat > "$DESKTOP_FILE" << EOF
[Desktop Entry]
Version=${LATEST_VERSION}
Type=Application
Name=Amethyst Mod Manager
Comment=Linux Mod Manager
Exec=${APPLICATIONS_DIR}/${APPIMAGE_NAME}
Icon=${ICONS_DIR}/${ICON_NAME}
Categories=Game;Utility;
Terminal=false
EOF

echo "Desktop entry created at $DESKTOP_FILE."
echo ""
echo "Installation complete. You can launch Amethyst Mod Manager from your application menu."