#!/usr/bin/env bash
#
# usync - Unified sync & setup for Ultimate Notetaking System
#
# SETUP (one-liner):
#   usync init <git-url> <age-key>
#   usync init git@server:user/config.git AGE-SECRET-KEY-1XXXXX...
#
# MOBILE PAIRING:
#   usync invite           # Show QR code for phone to scan
#   usync join             # Join from this device using invite
#
# SYNC:
#   usync                  # Sync everything
#   usync nb               # Sync only nb notebooks
#   usync st               # Sync only Syncthing folders
#   usync status           # Show sync status

set -euo pipefail

USYNC_DIR="${USYNC_DIR:-$HOME/.config/usync}"
USYNC_DEVICES="$USYNC_DIR/devices.json"

# Colors
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
BOLD='\033[1m'
DIM='\033[2m'
NC='\033[0m'

log_info()    { echo -e "${BLUE}::${NC} $1"; }
log_success() { echo -e "${GREEN}OK${NC} $1"; }
log_warn()    { echo -e "${YELLOW}!!${NC} $1"; }
log_error()   { echo -e "${RED}ERR${NC} $1" >&2; }
log_step()    { echo -e "${DIM}->>${NC} $1"; }

die() { log_error "$1"; exit 1; }

# Check dependencies
need_cmd() {
    command -v "$1" &>/dev/null || die "Required: $1 (not found)"
}

ensure_dir() {
    mkdir -p "$USYNC_DIR"
}

# ============================================================================
# INIT - Bootstrap new device from git repo + age key
# ============================================================================
cmd_init() {
    local git_url="${1:-}"
    local age_key="${2:-}"

    if [[ -z "$git_url" ]]; then
        echo "Usage: usync init <git-url> <age-key>"
        echo ""
        echo "Examples:"
        echo "  usync init git@server:user/config.git AGE-SECRET-KEY-1XXXX..."
        echo "  usync init https://git.example.com/user/config.git @/path/to/key.txt"
        echo ""
        echo "The age key can be:"
        echo "  - The key directly: AGE-SECRET-KEY-1..."
        echo "  - A file path with @: @/path/to/age-key.txt"
        exit 1
    fi

    if [[ -z "$age_key" ]]; then
        echo -n "Age secret key (or @/path/to/key.txt): "
        read -r age_key
    fi

    need_cmd git
    need_cmd age
    need_cmd sops

    ensure_dir

    log_info "Initializing device from $git_url"

    # Handle @file syntax for age key
    if [[ "$age_key" == @* ]]; then
        local keyfile="${age_key:1}"
        [[ -f "$keyfile" ]] || die "Key file not found: $keyfile"
        age_key=$(cat "$keyfile")
    fi

    # Validate age key format
    if [[ ! "$age_key" =~ ^AGE-SECRET-KEY-1[A-Z0-9]+$ ]]; then
        die "Invalid age key format. Expected: AGE-SECRET-KEY-1..."
    fi

    # Store age key securely
    local age_key_file="$USYNC_DIR/age-key.txt"
    echo "$age_key" > "$age_key_file"
    chmod 600 "$age_key_file"
    log_step "Stored age key"

    # Clone config repo
    local config_dir="$USYNC_DIR/config"
    if [[ -d "$config_dir" ]]; then
        log_step "Updating existing config..."
        git -C "$config_dir" pull --ff-only
    else
        log_step "Cloning config repo..."
        git clone "$git_url" "$config_dir"
    fi

    # Set up sops to use our age key
    export SOPS_AGE_KEY="$age_key"

    # Decrypt secrets if they exist
    if [[ -f "$config_dir/secrets/secrets.yaml" ]]; then
        log_step "Decrypting secrets..."
        sops -d "$config_dir/secrets/secrets.yaml" > "$USYNC_DIR/secrets.yaml"
        chmod 600 "$USYNC_DIR/secrets.yaml"
    fi

    # Get/generate device ID
    local device_id
    device_id=$(get_or_create_device_id)

    # Register this device
    register_device "$device_id"

    log_success "Device initialized!"
    echo ""
    echo "Your device ID:"
    echo -e "${BOLD}$device_id${NC}"
    echo ""
    echo "Next steps:"
    echo "  1. Add this device ID to other machines"
    echo "  2. Run: usync invite   # to pair mobile devices"
    echo "  3. Run: usync          # to sync"
}

# ============================================================================
# DEVICE ID MANAGEMENT
# ============================================================================
get_or_create_device_id() {
    # Try syncthing first
    if command -v syncthing &>/dev/null; then
        local st_id
        st_id=$(syncthing cli show system 2>/dev/null | jq -r '.myID // empty' 2>/dev/null || true)
        if [[ -n "$st_id" ]]; then
            echo "$st_id"
            return
        fi
    fi

    # Try to get from config
    local config_file="$HOME/.config/syncthing/config.xml"
    if [[ -f "$config_file" ]]; then
        local st_id
        st_id=$(grep -oP '(?<=<device id=")[^"]+' "$config_file" | head -1 || true)
        if [[ -n "$st_id" ]]; then
            echo "$st_id"
            return
        fi
    fi

    # Generate new syncthing keys if needed
    if command -v syncthing &>/dev/null; then
        log_step "Generating Syncthing device ID..."
        syncthing generate --skip-port-probing &>/dev/null || true
        syncthing cli show system 2>/dev/null | jq -r '.myID' 2>/dev/null || echo "UNKNOWN"
    else
        echo "UNKNOWN-$(hostname)-$(date +%s)"
    fi
}

register_device() {
    local device_id="$1"
    local hostname
    hostname=$(hostname)

    ensure_dir

    # Load or create devices file
    if [[ ! -f "$USYNC_DEVICES" ]]; then
        echo '{"devices":{}}' > "$USYNC_DEVICES"
    fi

    # Add this device
    local tmp
    tmp=$(mktemp)
    jq --arg id "$device_id" --arg name "$hostname" \
       '.devices[$name] = {id: $id, added: (now | todate)}' \
       "$USYNC_DEVICES" > "$tmp" && mv "$tmp" "$USYNC_DEVICES"

    log_step "Registered device: $hostname"
}

# ============================================================================
# INVITE - Generate QR/invite for mobile device
# ============================================================================
cmd_invite() {
    local device_id
    device_id=$(get_or_create_device_id)

    echo ""
    echo -e "${BOLD}=== Add Mobile Device ===${NC}"
    echo ""

    echo "Device ID:"
    echo -e "${GREEN}$device_id${NC}"
    echo ""

    # Generate QR code if qrencode is available
    if command -v qrencode &>/dev/null; then
        echo "Scan this QR code with Syncthing app:"
        echo ""
        qrencode -t ANSIUTF8 "$device_id"
        echo ""
    else
        log_warn "Install 'qrencode' for QR codes: nix-shell -p qrencode"
        echo ""
    fi

    echo -e "${DIM}--- Manual setup ---${NC}"
    echo ""
    echo "In Syncthing Android app:"
    echo "  1. Open Syncthing"
    echo "  2. Tap menu (3 dots) > Show device ID"
    echo "  3. Run on this machine:"
    echo ""
    echo -e "     ${BOLD}usync add-device <phone-device-id>${NC}"
    echo ""
    echo "  4. Back in app: Add Device > paste this ID:"
    echo ""
    echo -e "     ${GREEN}$device_id${NC}"
    echo ""

    # Show folders that can be shared
    if command -v syncthing &>/dev/null && syncthing cli show system &>/dev/null 2>&1; then
        local folders
        folders=$(syncthing cli show config 2>/dev/null | jq -r '.folders[].id' 2>/dev/null | tr '\n' ' ')
        if [[ -n "$folders" ]]; then
            echo "Available folders to share: $folders"
        fi
    fi
}

# ============================================================================
# ADD-DEVICE - Add a device by ID (for mobile pairing)
# ============================================================================
cmd_add_device() {
    local device_id="${1:-}"
    local device_name="${2:-mobile}"

    if [[ -z "$device_id" ]]; then
        echo "Usage: usync add-device <device-id> [name]"
        echo ""
        echo "Get the device ID from Syncthing app:"
        echo "  Menu > Show device ID"
        exit 1
    fi

    # Clean up device ID (remove spaces, lowercase)
    device_id=$(echo "$device_id" | tr -d ' \n' | tr '[:lower:]' '[:upper:]')

    # Validate format (basic check)
    if [[ ! "$device_id" =~ ^[A-Z0-9-]{52,63}$ ]]; then
        log_warn "Device ID looks unusual (expected 52-63 chars). Continuing anyway..."
    fi

    if command -v syncthing &>/dev/null && syncthing cli show system &>/dev/null 2>&1; then
        log_info "Adding device via Syncthing CLI..."

        # Add device to syncthing
        syncthing cli config devices add --device-id "$device_id" --name "$device_name"

        # Auto-accept folders from this device (convenient for mobile)
        syncthing cli config devices "$device_id" auto-accept-folders set true

        log_success "Added device: $device_name ($device_id)"
        echo ""
        echo "The device should appear in Syncthing shortly."
        echo "You may need to accept the connection on the mobile device."
    else
        # Store for later if syncthing not running
        register_device_manual "$device_id" "$device_name"
        log_success "Stored device: $device_name"
        echo "Device will be added when Syncthing starts."
    fi
}

register_device_manual() {
    local device_id="$1"
    local device_name="$2"

    ensure_dir

    if [[ ! -f "$USYNC_DEVICES" ]]; then
        echo '{"devices":{}}' > "$USYNC_DEVICES"
    fi

    local tmp
    tmp=$(mktemp)
    jq --arg id "$device_id" --arg name "$device_name" \
       '.devices[$name] = {id: $id, added: (now | todate), pending: true}' \
       "$USYNC_DEVICES" > "$tmp" && mv "$tmp" "$USYNC_DEVICES"
}

# ============================================================================
# JOIN - Join an existing setup (interactive, mobile-friendly output)
# ============================================================================
cmd_join() {
    echo ""
    echo -e "${BOLD}=== Join Existing Setup ===${NC}"
    echo ""

    local device_id
    device_id=$(get_or_create_device_id)

    echo "This device's ID:"
    echo ""
    echo -e "${GREEN}$device_id${NC}"
    echo ""

    # Generate QR for easy sharing
    if command -v qrencode &>/dev/null; then
        echo "Other devices can scan this:"
        qrencode -t ANSIUTF8 "$device_id"
        echo ""
    fi

    echo "To complete setup:"
    echo "  1. On another device, run:"
    echo -e "     ${BOLD}usync add-device $device_id $(hostname)${NC}"
    echo ""
    echo "  2. Or add manually in Syncthing GUI"
    echo ""

    echo -n "Press Enter when the other device has added you..."
    read -r

    # Trigger a rescan
    if command -v syncthing &>/dev/null && syncthing cli show system &>/dev/null 2>&1; then
        syncthing cli scan --all 2>/dev/null || true
    fi

    log_success "Done! Folders will sync automatically."
}

# ============================================================================
# SYNC COMMANDS (original functionality)
# ============================================================================
sync_nb() {
    log_info "Syncing nb notebooks..."

    if ! command -v nb &>/dev/null; then
        log_warn "nb not found"
        return 0
    fi

    local notebooks
    notebooks=$(nb notebooks --names 2>/dev/null || echo "")

    if [[ -z "$notebooks" ]]; then
        log_warn "No nb notebooks found"
        return 0
    fi

    for notebook in $notebooks; do
        log_step "Syncing: $notebook"
        if nb "$notebook:sync" 2>/dev/null; then
            log_success "$notebook"
        else
            log_warn "$notebook (no remote?)"
        fi
    done
}

sync_syncthing() {
    log_info "Triggering Syncthing scan..."

    if ! command -v syncthing &>/dev/null; then
        log_warn "syncthing not found"
        return 0
    fi

    if ! syncthing cli show system &>/dev/null 2>&1; then
        log_warn "Syncthing not running"
        return 0
    fi

    if syncthing cli scan --all 2>/dev/null; then
        log_success "Scan triggered"
    else
        log_warn "Scan failed"
    fi
}

show_status() {
    echo -e "${BOLD}=== Sync Status ===${NC}"
    echo ""

    # Device ID
    local device_id
    device_id=$(get_or_create_device_id 2>/dev/null || echo "unknown")
    echo -e "This device: ${DIM}${device_id:0:20}...${NC}"
    echo ""

    # nb
    echo "nb notebooks:"
    if command -v nb &>/dev/null; then
        local nb_dir="${NB_DIR:-$HOME/.nb}"
        for notebook in $(nb notebooks --names 2>/dev/null || true); do
            if [[ -d "$nb_dir/$notebook/.git" ]]; then
                local last
                last=$(git -C "$nb_dir/$notebook" log -1 --format="%ar" 2>/dev/null || echo "never")
                echo -e "  ${GREEN}*${NC} $notebook (synced $last)"
            else
                echo -e "  ${YELLOW}*${NC} $notebook (local only)"
            fi
        done
    else
        echo "  (nb not installed)"
    fi

    echo ""

    # Syncthing
    echo "Syncthing:"
    if command -v syncthing &>/dev/null && syncthing cli show system &>/dev/null 2>&1; then
        local folders
        folders=$(syncthing cli show config 2>/dev/null | jq -r '.folders[] | "  \(.id): \(.path)"' 2>/dev/null || echo "  (error)")
        echo "$folders"

        echo ""
        echo "Connected devices:"
        syncthing cli show connections 2>/dev/null | jq -r '.connections | to_entries[] | select(.value.connected) | "  \(.key[:15])... (\(.value.type))"' 2>/dev/null || echo "  (none)"
    else
        echo "  (not running)"
    fi
}

# ============================================================================
# MAIN
# ============================================================================
show_help() {
    cat <<'EOF'
usync - Unified sync & setup

SETUP (first time):
  usync init <git-url> <age-key>   Bootstrap from config repo
  usync join                        Join existing setup (shows QR)

PAIRING:
  usync invite                      Show QR code for mobile to scan
  usync add-device <id> [name]      Add a device by ID

SYNC:
  usync                             Sync everything
  usync nb                          Sync nb notebooks only
  usync st                          Sync Syncthing only
  usync status                      Show sync status

EXAMPLES:
  # Bootstrap new desktop from config repo:
  usync init git@server:me/config.git AGE-SECRET-KEY-1XXXX...

  # Pair mobile phone:
  usync invite                      # on desktop, scan QR with phone
  usync add-device XXXXX mobile     # after getting phone's ID

  # Daily sync:
  usync
EOF
}

case "${1:-sync}" in
    init)
        shift
        cmd_init "$@"
        ;;
    invite|pair|qr)
        cmd_invite
        ;;
    add-device|add)
        shift
        cmd_add_device "$@"
        ;;
    join)
        cmd_join
        ;;
    nb)
        sync_nb
        ;;
    st|syncthing)
        sync_syncthing
        ;;
    status|s)
        show_status
        ;;
    sync|"")
        sync_nb
        echo ""
        sync_syncthing
        ;;
    -h|--help|help)
        show_help
        ;;
    *)
        log_error "Unknown command: $1"
        echo "Run 'usync help' for usage"
        exit 1
        ;;
esac