#!/bin/bash
# ABOUTME: Transforms an existing Arch+Wayland system into a Moonarch system.
# ABOUTME: Backs up configs, installs moonarch-git package, deploys user configs with hard overwrite.

set -euo pipefail

source "$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/lib.sh"

# --- Parse arguments ---

DRY_RUN=false
if [[ "${1:-}" == "--dry-run" ]]; then
    DRY_RUN=true
fi

# ============================================================
# Phase 1: Prerequisites & Detection
# ============================================================

check_not_root
check_pacman

# Require active Wayland session
if [[ "${XDG_SESSION_TYPE:-}" != "wayland" ]] && [[ -z "${WAYLAND_DISPLAY:-}" ]]; then
    err "No active Wayland session detected. Transform requires Wayland."
    exit 1
fi

# Detect conflicting display managers
CONFLICTING_DMS=()
for dm in sddm gdm lightdm ly lemurs; do
    if systemctl is-enabled "${dm}.service" &>/dev/null; then
        CONFLICTING_DMS+=("$dm")
    fi
done

# Detect conflicting packages
CONFLICTING_PKGS=()
if pacman -Qq pulseaudio &>/dev/null && ! pacman -Qq pipewire-pulse &>/dev/null; then
    CONFLICTING_PKGS+=("pulseaudio")
fi

# ============================================================
# Phase 2: Pre-flight Summary
# ============================================================

echo ""
if $DRY_RUN; then
    log "============================================"
    log "  Moonarch Transform — Dry Run"
    log "============================================"
else
    log "============================================"
    log "  Moonarch Transform — Pre-flight Summary"
    log "============================================"
fi
echo ""

log "Wayland session:    detected"

if [[ ${#CONFLICTING_DMS[@]} -gt 0 ]]; then
    log "Display managers:   ${CONFLICTING_DMS[*]} (will be disabled)"
else
    log "Display managers:   none conflicting"
fi

if [[ ${#CONFLICTING_PKGS[@]} -gt 0 ]]; then
    log "Package conflicts:  ${CONFLICTING_PKGS[*]} (will be removed)"
else
    log "Package conflicts:  none"
fi

echo ""
log "Actions:"
log "  1. (Optional) Backup ~/.config/, ~/.zshrc, /etc/xdg/"
log "  2. Install moonarch-git package (pulls in all dependencies)"
log "  3. Disable conflicting DMs, enable greetd"
log "  4. Overwrite ALL user configs (~/.config/)"
log "  5. Configure GTK themes, firewall, services"
echo ""

# Show package diff
MISSING_OFFICIAL=$(comm -23 <(read_packages "$OFFICIAL_PACKAGES" | sort) <(pacman -Qqe | sort) 2>/dev/null || true)
MISSING_AUR=""
if [[ -f "$AUR_PACKAGES" ]]; then
    MISSING_AUR=$(comm -23 <(read_packages "$AUR_PACKAGES" | sort) <(pacman -Qqe | sort) 2>/dev/null || true)
fi

if [[ -n "$MISSING_OFFICIAL" ]] || [[ -n "$MISSING_AUR" ]]; then
    log "Packages to install:"
    if [[ -n "$MISSING_OFFICIAL" ]]; then
        OFFICIAL_COUNT=$(echo "$MISSING_OFFICIAL" | wc -l)
        log "  Official ($OFFICIAL_COUNT):"
        echo "$MISSING_OFFICIAL" | sed 's/^/    /'
    fi
    if [[ -n "$MISSING_AUR" ]]; then
        AUR_COUNT=$(echo "$MISSING_AUR" | wc -l)
        log "  AUR ($AUR_COUNT):"
        echo "$MISSING_AUR" | sed 's/^/    /'
    fi
else
    log "Packages:           all already installed"
fi

# Show config diff summary
CHANGED_XDG=0
CHANGED_BIN=0
for src_dir in "$DEFAULTS_DIR/xdg/"*/; do
    app_name="$(basename "$src_dir")"
    dest_dir="$HOME/.config/$app_name"
    if [[ -d "$dest_dir" ]]; then
        if ! diff -rq "$src_dir" "$dest_dir" &>/dev/null 2>&1; then
            ((CHANGED_XDG++)) || true
        fi
    else
        ((CHANGED_XDG++)) || true
    fi
done
for bin in "$DEFAULTS_DIR/bin/moonarch-"*; do
    name=$(basename "$bin")
    if ! cmp -s "$bin" "/usr/bin/$name" 2>/dev/null; then
        ((CHANGED_BIN++)) || true
    fi
done
log "Config changes:     $CHANGED_XDG XDG app(s), $CHANGED_BIN helper script(s)"

echo ""
err "This will REPLACE your current desktop configuration."
echo ""

if $DRY_RUN; then
    log "Dry run complete — no changes were made."
    exit 0
fi

if ! confirm "Proceed?"; then
    log "Transform cancelled."
    exit 0
fi

# ============================================================
# Phase 3: Backup (optional)
# ============================================================

BACKUP_FILE=""
SYSTEM_BACKUP=""

if confirm "Create backup of current configs before overwriting?"; then
    BACKUP_FILE="$HOME/moonarch-backup-$(date +%Y%m%d-%H%M%S).tar.gz"
    log "Creating backup: $BACKUP_FILE"

    # Build list of paths that actually exist
    BACKUP_PATHS=()
    [[ -d "$HOME/.config" ]] && BACKUP_PATHS+=(".config")
    [[ -f "$HOME/.zshrc" ]] && BACKUP_PATHS+=(".zshrc")
    [[ -d "$HOME/.zshrc.d" ]] && BACKUP_PATHS+=(".zshrc.d")

    if [[ ${#BACKUP_PATHS[@]} -gt 0 ]]; then
        tar czf "$BACKUP_FILE" -C "$HOME" "${BACKUP_PATHS[@]}"
        log "  + User configs backed up."
    fi

    # Backup system XDG separately (needs sudo)
    if [[ -d /etc/xdg ]]; then
        SYSTEM_BACKUP="$HOME/moonarch-backup-system-$(date +%Y%m%d-%H%M%S).tar.gz"
        sudo tar czf "$SYSTEM_BACKUP" -C / etc/xdg
        sudo chown "$USER:$USER" "$SYSTEM_BACKUP"
        log "  + System configs backed up: $SYSTEM_BACKUP"
    fi

    log "Backup complete: $(du -h "$BACKUP_FILE" | cut -f1)"
else
    log "Skipping backup."
fi

# ============================================================
# Phase 4: Disable Conflicting Display Managers
# ============================================================

if [[ ${#CONFLICTING_DMS[@]} -gt 0 ]]; then
    log "Disabling conflicting display managers..."
    for dm in "${CONFLICTING_DMS[@]}"; do
        sudo systemctl disable "$dm"
        log "  - $dm disabled"
    done
fi

# ============================================================
# Phase 5: Remove Conflicting Packages
# ============================================================

if pacman -Qq pulseaudio &>/dev/null; then
    log "Removing PulseAudio (replaced by PipeWire)..."
    sudo pacman -Rdd --noconfirm pulseaudio pulseaudio-alsa pulseaudio-bluetooth 2>/dev/null || true
fi

# ============================================================
# Phase 6: Install moonarch-git Package
# ============================================================

# Install paru if not present
if ! command -v paru &>/dev/null; then
    log "Installing paru..."
    sudo pacman -S --needed --noconfirm paru
else
    log "paru already installed."
fi

# Moonarch package registry
log "Setting up Moonarch package registry..."
if ! grep -q '\[moonarch\]' /etc/pacman.conf 2>/dev/null; then
    sudo tee -a /etc/pacman.conf > /dev/null <<'EOCONF'

[moonarch]
SigLevel = Required DatabaseOptional
Server = https://gitea.moonarch.de/api/packages/nevaforget/arch/$repo/$arch
EOCONF
    log "  + Moonarch repo added to pacman.conf."
else
    log "  ~ Moonarch repo already in pacman.conf."
fi

log "Importing Moonarch registry signing key..."
EXPECTED_FINGERPRINT="9B02C596A4652C40CA768E75B90C8B82EA30A131"
KEY_FILE=$(mktemp)
trap 'rm -f "$KEY_FILE"' EXIT
curl -sf https://gitea.moonarch.de/api/packages/nevaforget/arch/repository.key -o "$KEY_FILE"
if [[ ! -s "$KEY_FILE" ]]; then
    err "Failed to download registry key (empty response)."
    exit 1
fi
KEY_FPR=$(gpg --show-keys --with-colons "$KEY_FILE" 2>/dev/null | awk -F: '/^fpr/{print $10; exit}')
if [[ "$KEY_FPR" != "$EXPECTED_FINGERPRINT" ]]; then
    err "Registry key fingerprint mismatch! Expected $EXPECTED_FINGERPRINT, got ${KEY_FPR:-<empty>}"
    exit 1
fi
KEY_ID=$(gpg --show-keys --with-colons "$KEY_FILE" 2>/dev/null | awk -F: '/^pub/{print $5}')
if [[ -n "$KEY_ID" ]] && ! sudo pacman-key --list-keys "$KEY_ID" &>/dev/null; then
    sudo pacman-key --add "$KEY_FILE"
    sudo pacman-key --lsign-key "$KEY_ID"
    log "  + Registry key $KEY_ID imported and locally signed."
else
    log "  ~ Registry key already imported."
fi
rm -f "$KEY_FILE"
trap - EXIT

# Install/update moonarch-git (paru repo config is set up by moonarch.install hook)
paru -Syu --pkgbuilds --noconfirm

log "Installing moonarch-git package..."
paru -S --needed --noconfirm moonarch-git

# Install packages from package lists
if [[ -n "$MISSING_OFFICIAL" ]]; then
    log "Installing official packages..."
    echo "$MISSING_OFFICIAL" | paru -S --needed --noconfirm -
fi

if [[ -n "$MISSING_AUR" ]]; then
    log "Installing AUR packages..."
    echo "$MISSING_AUR" | paru -S --needed --noconfirm -
fi

# ============================================================
# Phase 7: User-Level Configuration
# ============================================================

# User-level GTK4 symlinks for libadwaita apps
THEME_NAME="Colloid-Grey-Dark-Catppuccin"
THEME_GTK4="/usr/share/themes/$THEME_NAME/gtk-4.0"

if [[ -d "$THEME_GTK4" ]]; then
    log "Creating user-level GTK4 symlinks for $THEME_NAME..."
    USER_GTK4="$HOME/.config/gtk-4.0"
    mkdir -p "$USER_GTK4"
    ln -sf "$THEME_GTK4/gtk-dark.css" "$USER_GTK4/gtk.css"
    ln -sf "$THEME_GTK4/gtk-dark.css" "$USER_GTK4/gtk-dark.css"
    rm -f "$USER_GTK4/assets"
    ln -s "$THEME_GTK4/assets" "$USER_GTK4/assets"
else
    err "GTK4 theme not found: $THEME_GTK4 — libadwaita apps will use fallback theme."
fi

# gsettings
log "Setting gsettings for GTK theme..."
gsettings set org.gnome.desktop.interface gtk-theme "$THEME_NAME"
gsettings set org.gnome.desktop.interface color-scheme 'prefer-dark'
gsettings set org.gnome.desktop.interface icon-theme 'Colloid-Grey-Catppuccin-Dark'
gsettings set org.gnome.desktop.interface font-name 'UbuntuSans Nerd Font 11'

# ============================================================
# Phase 8: Deploy User Configs (Hard Overwrite)
# ============================================================

# Replace user-level XDG configs from /etc/xdg/ (deployed by moonarch-git)
log "Deploying XDG configs to ~/.config/ (overwrite)..."
for src_dir in /etc/xdg/*/; do
    app_name="$(basename "$src_dir")"
    # Only overwrite apps that moonarch manages
    [[ -d "$DEFAULTS_DIR/xdg/$app_name" ]] || continue
    # gtk-4.0 is handled separately with Colloid-Grey-Dark-Catppuccin theme symlinks
    [[ "$app_name" == "gtk-4.0" ]] && continue
    # kanshi profiles are user-specific (display setup) — only seed, never overwrite
    [[ "$app_name" == "kanshi" ]] && [[ -d "$HOME/.config/kanshi" ]] && continue
    dest_dir="$HOME/.config/$app_name"
    rm -rf "$dest_dir" 2>/dev/null || sudo rm -rf "$dest_dir"
    cp -r --no-preserve=ownership "$src_dir" "$dest_dir"
    log "  + $app_name/"
done

# Overwrite configs owned by other packages with moonarch versions
log "Deploying moonarch config overrides..."
cp /usr/share/moonarch/walker-config.toml "$HOME/.config/walker/config.toml"
log "  + walker/config.toml"

# Zsh: always create a fresh .zshrc that sources Moonarch defaults
log "Creating ~/.zshrc with Moonarch defaults..."
mkdir -p "$HOME/.zshrc.d"
echo "# Load Moonarch defaults, add custom overrides in ~/.zshrc.d/ or below" > "$HOME/.zshrc"
echo "source /etc/zsh/zshrc.moonarch" >> "$HOME/.zshrc"

# ============================================================
# Phase 9: Services & Finalization
# ============================================================

# Enable systemd user services
log "Enabling systemd user services..."
USER_SERVICES=(
    "kanshi"
    "stasis"
    "cliphist-text"
    "cliphist-image"
)

for service in "${USER_SERVICES[@]}"; do
    if systemctl --user cat "${service}.service" &>/dev/null; then
        systemctl --user enable "$service"
        log "  + $service (user)"
    else
        log "  ~ $service (user) not found, skipped."
    fi
done

log "Enabling services..."
SERVICES=(
    "NetworkManager"
    "bluetooth"
    "greetd"
    "systemd-timesyncd"
    "ufw"
    "auto-cpufreq"
)

for service in "${SERVICES[@]}"; do
    if systemctl list-unit-files "${service}.service" &>/dev/null; then
        sudo systemctl enable "$service"
        log "  + $service"
    else
        log "  ~ $service not found, skipped."
    fi
done

# Set shell to zsh
if [[ "$SHELL" != */zsh ]]; then
    log "Setting default shell to zsh..."
    chsh -s "$(which zsh)"
fi

# Firewall
log "Configuring UFW..."
sudo ufw default deny incoming
sudo ufw default allow outgoing
sudo ufw --force enable

# Directories
mkdir -p "$HOME/Pictures/Screenshots"
mkdir -p "$HOME/Pictures/Wallpaper"

# ============================================================
# Phase 10: Done
# ============================================================

echo ""
log "============================================"
log "  Moonarch transform complete!"
log "============================================"
echo ""
if [[ -n "$BACKUP_FILE" ]]; then
    log "Your previous config is backed up at:"
    log "  $BACKUP_FILE"
    if [[ -n "$SYSTEM_BACKUP" ]]; then
        log "  $SYSTEM_BACKUP"
    fi
fi
echo ""
log "Next steps:"
log "  1. Reboot (greetd replaces your previous display manager)"
log "  2. Place wallpapers in ~/Pictures/Wallpaper/"
log "  3. rustup default stable"
log "  4. User overrides in ~/.config/ or ~/.zshrc.d/"
echo ""
err "Do NOT log out — your previous DM is disabled. Reboot instead."
echo ""