#!/usr/bin/env bash
#
# setup - One command setup for Ultimate Notetaking System
#
# Usage:
#   ./setup                     # Interactive setup
#   ./setup <url> <age-key>     # Non-interactive join
#   ./setup mobile              # Pair mobile device
#
set -euo pipefail

# Colors
R='\033[0;31m' G='\033[0;32m' Y='\033[1;33m' B='\033[0;34m'
BOLD='\033[1m' DIM='\033[2m' NC='\033[0m'

info()  { echo -e "${B}::${NC} $1"; }
ok()    { echo -e "${G}OK${NC} $1"; }
warn()  { echo -e "${Y}!!${NC} $1"; }
err()   { echo -e "${R}ERR${NC} $1" >&2; }
step()  { echo -e "${DIM}->>${NC} $1"; }

# Config
USYNC_DIR="$HOME/.config/usync"
AGE_KEY_FILE="$USYNC_DIR/age-key.txt"

has() { command -v "$1" &>/dev/null; }

ensure_deps() {
    local missing=()
    for cmd in git jq; do
        has "$cmd" || missing+=("$cmd")
    done

    if [[ ${#missing[@]} -gt 0 ]]; then
        err "Missing: ${missing[*]}"
        echo "Install with: nix-shell -p ${missing[*]}"
        exit 1
    fi

    # Optional but recommended
    has syncthing || warn "syncthing not found - file sync won't work"
    has age || warn "age not found - install for secret management"
    has qrencode || warn "qrencode not found - QR codes won't work"
}

get_device_id() {
    if has syncthing; then
        # Try running instance
        local id
        id=$(syncthing cli show system 2>/dev/null | jq -r '.myID // empty' 2>/dev/null || true)
        [[ -n "$id" ]] && { echo "$id"; return; }

        # Try config file
        local cfg="$HOME/.config/syncthing/config.xml"
        if [[ -f "$cfg" ]]; then
            id=$(grep -oP '(?<=<device id=")[^"]+' "$cfg" 2>/dev/null | head -1 || true)
            [[ -n "$id" ]] && { echo "$id"; return; }
        fi

        # Generate new
        step "Generating Syncthing identity..."
        syncthing generate --skip-port-probing &>/dev/null || true
        syncthing cli show system 2>/dev/null | jq -r '.myID' 2>/dev/null || echo ""
    fi
}

# =============================================================================
# SETUP NEW (first device)
# =============================================================================
setup_new() {
    echo ""
    echo -e "${BOLD}Setting up first device...${NC}"
    echo ""

    mkdir -p "$USYNC_DIR"

    # Generate age key
    if [[ -f "$AGE_KEY_FILE" ]]; then
        warn "Age key already exists at $AGE_KEY_FILE"
    else
        if has age-keygen; then
            step "Generating age encryption key..."
            age-keygen -o "$AGE_KEY_FILE" 2>&1 | grep "public key"
            chmod 600 "$AGE_KEY_FILE"
        else
            err "age not installed. Run: nix-shell -p age"
            exit 1
        fi
    fi

    # Get/create syncthing ID
    local device_id
    device_id=$(get_device_id)

    # Create local config structure
    local config_dir="$USYNC_DIR/config"
    if [[ ! -d "$config_dir" ]]; then
        step "Creating config structure..."
        mkdir -p "$config_dir/hosts/$(hostname)" "$config_dir/secrets"

        # Create minimal secrets template
        cat > "$config_dir/secrets/secrets.yaml" <<'EOF'
# Encrypted with sops - edit with: sops secrets/secrets.yaml
restic-password: "changeme"
EOF

        # Init git repo
        git -C "$config_dir" init -q
        git -C "$config_dir" add -A
        git -C "$config_dir" commit -q -m "Initial setup"
    fi

    # Summary
    echo ""
    echo -e "${G}=== Setup Complete ===${NC}"
    echo ""
    echo "Your age key (SAVE THIS SOMEWHERE SAFE):"
    echo -e "${BOLD}$(cat "$AGE_KEY_FILE" | grep 'AGE-SECRET-KEY')${NC}"
    echo ""
    if [[ -n "$device_id" ]]; then
        echo "Device ID: ${device_id:0:20}..."
    fi
    echo ""
    echo "Next steps:"
    echo "  1. Push config to git server:"
    echo "     cd $config_dir && git remote add origin <your-git-url> && git push -u origin main"
    echo ""
    echo "  2. On other devices, run:"
    echo "     ./setup <git-url> <age-key>"
    echo ""
    echo "  3. To pair mobile:"
    echo "     ./setup mobile"
}

# =============================================================================
# SETUP JOIN (existing setup)
# =============================================================================
setup_join() {
    local git_url="$1"
    local age_key="$2"

    echo ""
    echo -e "${BOLD}Joining existing setup...${NC}"
    echo ""

    mkdir -p "$USYNC_DIR"

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

    # Save age key
    echo "$age_key" > "$AGE_KEY_FILE"
    chmod 600 "$AGE_KEY_FILE"
    step "Saved age key"

    # Clone config
    local config_dir="$USYNC_DIR/config"
    if [[ -d "$config_dir" ]]; then
        step "Updating config..."
        git -C "$config_dir" pull --ff-only 2>/dev/null || git -C "$config_dir" fetch
    else
        step "Cloning config..."
        git clone "$git_url" "$config_dir"
    fi

    # Decrypt secrets
    if has sops && [[ -f "$config_dir/secrets/secrets.yaml" ]]; then
        step "Decrypting secrets..."
        export SOPS_AGE_KEY="$age_key"
        sops -d "$config_dir/secrets/secrets.yaml" > "$USYNC_DIR/secrets.yaml" 2>/dev/null || warn "Could not decrypt secrets"
        chmod 600 "$USYNC_DIR/secrets.yaml" 2>/dev/null || true
    fi

    # Setup syncthing
    local device_id
    device_id=$(get_device_id)

    # Register device
    local devices_file="$USYNC_DIR/devices.json"
    echo "{\"devices\":{\"$(hostname)\":{\"id\":\"$device_id\",\"added\":\"$(date -Iseconds)\"}}}" > "$devices_file"

    echo ""
    echo -e "${G}=== Joined! ===${NC}"
    echo ""
    if [[ -n "$device_id" ]]; then
        echo "This device: ${device_id:0:20}..."
        echo ""
        echo "Add this device on your other machines:"
        echo -e "  ${BOLD}./setup add $device_id $(hostname)${NC}"
    fi
    echo ""
    echo "To pair mobile: ./setup mobile"
    echo "To sync:        ./scripts/usync"
}

# =============================================================================
# MOBILE PAIRING
# =============================================================================
scan_qr_camera() {
    # Check for video devices
    if [[ ! -e /dev/video0 ]]; then
        err "No camera found (/dev/video0 doesn't exist)" >&2
        return 1
    fi

    if ! has ffmpeg; then
        err "ffmpeg not found. Run: nix-shell -p ffmpeg zbar" >&2
        return 1
    fi
    if ! has zbarimg; then
        err "zbarimg not found. Run: nix-shell -p zbar" >&2
        return 1
    fi

    local tmpdir="/tmp/usync_qr_$$"
    local result_file="$tmpdir/result"
    local ffmpeg_pid=""

    mkdir -p "$tmpdir"

    cleanup_camera() {
        [[ -n "$ffmpeg_pid" ]] && kill "$ffmpeg_pid" 2>/dev/null || true
        rm -rf "$tmpdir"
    }
    trap cleanup_camera RETURN EXIT

    echo "" >&2
    echo "Point camera at QR code - it will scan automatically." >&2
    echo "(Press Ctrl+C to cancel)" >&2
    echo "" >&2

    # Start ffmpeg: show preview with crosshair AND save frames for scanning
    ffmpeg -f v4l2 -video_size 640x480 -i /dev/video0 \
        -vf "drawbox=x=iw/2-100:y=ih/2-100:w=200:h=200:color=green:t=3" \
        -f sdl2 -window_title "Scan QR Code" - \
        -vf "fps=2" -update 1 -q:v 2 "$tmpdir/frame.jpg" \
        -loglevel quiet 2>/dev/null &
    ffmpeg_pid=$!

    sleep 1  # Let camera warm up

    # Scan frames as they're captured
    for attempt in {1..60}; do
        sleep 0.5

        # Check if ffmpeg died
        if ! kill -0 "$ffmpeg_pid" 2>/dev/null; then
            break
        fi

        if [[ -f "$tmpdir/frame.jpg" ]]; then
            local result
            result=$(zbarimg --raw -q "$tmpdir/frame.jpg" 2>/dev/null || true)

            if [[ -n "$result" ]]; then
                result=$(echo "$result" | tr -d ' \n\r' | tr '[:lower:]' '[:upper:]')

                if [[ "$result" =~ ^[A-Z0-9]{7}-[A-Z0-9]{7}-[A-Z0-9]{7}-[A-Z0-9]{7}-[A-Z0-9]{7}-[A-Z0-9]{7}-[A-Z0-9]{7}-[A-Z0-9]{7}$ ]]; then
                    echo "" >&2
                    ok "Scanned!" >&2
                    echo "$result"
                    return 0
                fi
            fi
        fi
    done

    echo "" >&2
    warn "No QR code detected (timed out after 30s)" >&2
    return 1
}

check_pending_devices() {
    if ! has syncthing || ! syncthing cli show system &>/dev/null 2>&1; then
        return 1
    fi

    # Get pending devices (devices trying to connect that we haven't approved)
    local pending
    pending=$(syncthing cli show pending devices 2>/dev/null || true)

    if [[ -n "$pending" && "$pending" != "{}" && "$pending" != "null" ]]; then
        echo "$pending" | jq -r 'to_entries[] | "\(.key)|\(.value.name // "unknown")"' 2>/dev/null
        return 0
    fi
    return 1
}

check_local_discovery() {
    if ! has syncthing || ! syncthing cli show system &>/dev/null 2>&1; then
        return 1
    fi

    # Check discovery cache for LAN devices
    local discovery
    discovery=$(syncthing cli show discovery 2>/dev/null || true)

    if [[ -n "$discovery" && "$discovery" != "{}" && "$discovery" != "null" ]]; then
        echo "$discovery" | jq -r 'to_entries[] | select(.value[] | contains("tcp://192.") or contains("tcp://10.") or contains("tcp://172.")) | .key' 2>/dev/null | head -5
        return 0
    fi
    return 1
}

add_phone_device() {
    local phone_id="$1"
    local name="${2:-phone}"

    phone_id=$(echo "$phone_id" | tr -d ' \n' | tr '[:lower:]' '[:upper:]')

    if has syncthing && syncthing cli show system &>/dev/null 2>&1; then
        syncthing cli config devices add --device-id "$phone_id" --name "$name" 2>/dev/null || true
        syncthing cli config devices "$phone_id" auto-accept-folders set true 2>/dev/null || true
        ok "Added: $name"
        return 0
    else
        mkdir -p "$USYNC_DIR"
        echo "$phone_id" > "$USYNC_DIR/pending-phone.id"
        ok "Saved (will add when syncthing starts)"
        return 0
    fi
}

setup_mobile() {
    echo ""
    echo -e "${BOLD}=== Pair Mobile Device ===${NC}"
    echo ""

    local device_id
    device_id=$(get_device_id)

    if [[ -z "$device_id" ]]; then
        err "Could not get device ID. Is syncthing installed?"
        exit 1
    fi

    # Check for pending devices first (phone already trying to connect)
    local pending
    pending=$(check_pending_devices 2>/dev/null || true)

    if [[ -n "$pending" ]]; then
        echo -e "${G}Found device(s) waiting to connect:${NC}"
        echo ""
        local i=1
        declare -a pending_ids
        while IFS='|' read -r id name; do
            echo "  [$i] $name (${id:0:20}...)"
            pending_ids+=("$id")
            ((i++))
        done <<< "$pending"
        echo ""
        echo -n "Accept which? [1-$((i-1))], or Enter to continue: "
        read -r choice

        if [[ -n "$choice" && "$choice" =~ ^[0-9]+$ && "$choice" -ge 1 && "$choice" -lt "$i" ]]; then
            local selected_id="${pending_ids[$((choice-1))]}"
            add_phone_device "$selected_id" "phone"
            echo ""
            ok "Mobile pairing complete!"
            return
        fi
        echo ""
    fi

    # Step 1: Show computer's ID for phone
    echo -e "${BOLD}Step 1: Add this computer on your phone${NC}"
    echo ""
    echo "Computer's Device ID:"
    echo ""
    echo -e "${G}$device_id${NC}"
    echo ""

    if has qrencode; then
        echo "Or scan this QR in Syncthing app:"
        echo ""
        qrencode -t ANSIUTF8 "$device_id"
    fi

    echo ""
    echo "In Syncthing app: tap (+) > paste or scan above"
    echo ""
    echo -n "Press Enter when done..."
    read -r

    # Step 2: Get phone's ID
    echo ""
    echo -e "${BOLD}Step 2: Add your phone on this computer${NC}"
    echo ""
    echo "In Syncthing app: Menu (3 dots) > Show device ID"
    echo ""

    # Try camera first if available
    if has zbarimg && has ffmpeg && [[ -e /dev/video0 ]]; then
        echo "  [1] Scan phone's QR with camera"
        echo "  [2] Paste phone's device ID"
        echo ""
        echo -n "Choice [1/2]: "
        read -r method

        if [[ "$method" == "1" ]]; then
            local scanned
            if scanned=$(scan_qr_camera); then
                add_phone_device "$scanned" "phone"
                echo ""
                ok "Pairing complete! Devices should connect shortly."
                return
            fi
            echo ""
            echo "Camera didn't work. Paste the ID instead:"
        fi
    fi

    echo -n "Paste phone's device ID: "
    read -r phone_id

    if [[ -n "$phone_id" ]]; then
        add_phone_device "$phone_id" "phone"
        echo ""
        ok "Pairing complete! Devices should connect shortly."
    else
        warn "No ID entered. Run './setup mobile' to try again."
    fi
}

# =============================================================================
# ADD DEVICE
# =============================================================================
add_device() {
    local device_id="$1"
    local name="${2:-device}"

    device_id=$(echo "$device_id" | tr -d ' \n' | tr '[:lower:]' '[:upper:]')

    if has syncthing && syncthing cli show system &>/dev/null 2>&1; then
        syncthing cli config devices add --device-id "$device_id" --name "$name"
        syncthing cli config devices "$device_id" auto-accept-folders set true
        ok "Added device: $name"
    else
        mkdir -p "$USYNC_DIR"
        echo "{\"id\":\"$device_id\",\"name\":\"$name\"}" >> "$USYNC_DIR/pending-devices.json"
        ok "Saved device (will add when syncthing runs)"
    fi
}

# =============================================================================
# INTERACTIVE
# =============================================================================
interactive() {
    echo ""
    echo -e "${BOLD}Ultimate Notetaking System - Setup${NC}"
    echo ""
    echo "  [1] New setup (first device)"
    echo "  [2] Join existing setup"
    echo "  [3] Pair mobile device"
    echo ""
    echo -n "Choice [1/2/3]: "
    read -r choice

    case "$choice" in
        1|n|new)
            setup_new
            ;;
        2|j|join)
            echo ""
            echo -n "Config git URL: "
            read -r git_url
            echo -n "Age secret key: "
            read -r age_key
            setup_join "$git_url" "$age_key"
            ;;
        3|m|mobile)
            setup_mobile
            ;;
        *)
            err "Invalid choice"
            exit 1
            ;;
    esac
}

# =============================================================================
# MAIN
# =============================================================================
ensure_deps

case "${1:-}" in
    "")
        interactive
        ;;
    mobile|phone|m)
        setup_mobile
        ;;
    add)
        [[ -z "${2:-}" ]] && { err "Usage: ./setup add <device-id> [name]"; exit 1; }
        add_device "$2" "${3:-}"
        ;;
    help|-h|--help)
        cat <<'EOF'
setup - One command setup

Usage:
  ./setup                       Interactive setup
  ./setup <url> <key>           Join existing setup
  ./setup mobile                Pair mobile device
  ./setup add <id> [name]       Add a device

Examples:
  ./setup                                           # Interactive
  ./setup git@srv:me/cfg.git AGE-SECRET-KEY-1...    # Join
  ./setup mobile                                    # Pair phone
EOF
        ;;
    *)
        # Assume it's: ./setup <url> <key>
        if [[ -n "${2:-}" ]]; then
            setup_join "$1" "$2"
        else
            err "Usage: ./setup <git-url> <age-key>"
            exit 1
        fi
        ;;
esac