#!/bin/bash
# PDF Presentation with Auto-Advance
# Works for both native PDF and converted PPTX files

PDF_FILE="$1"
INTERVAL="${2:-10}"
LOOP="${3:-false}"

if [ -z "$PDF_FILE" ]; then
    echo "Usage: $0 <file.pdf> [interval-seconds] [loop:true|false]"
    exit 1
fi

if [ ! -f "$PDF_FILE" ]; then
    echo "Error: File not found: $PDF_FILE"
    exit 1
fi

echo "=========================================="
echo "  PDF Presentation Mode"
echo "=========================================="
echo ""
echo "File: $(basename "$PDF_FILE")"
echo "Auto-advance: ${INTERVAL}s per slide"
echo "Loop: $LOOP"
echo ""

# Count pages in PDF
PAGE_COUNT=$(pdfinfo "$PDF_FILE" 2>/dev/null | grep "Pages:" | awk '{print $2}')

if [ -z "$PAGE_COUNT" ] || [ "$PAGE_COUNT" -eq 0 ]; then
    echo "Warning: Could not determine page count, assuming 10 pages"
    PAGE_COUNT=10
else
    echo "Detected $PAGE_COUNT pages"
fi

echo ""

# Check for required tools
if ! command -v xdotool &> /dev/null; then
    echo "Error: xdotool not installed"
    echo "Install with: sudo apt-get install xdotool"
    exit 1
fi

# Choose best PDF viewer (prefer Impressive for auto-advance)
PDF_VIEWER=""
PDF_VIEWER_CMD=""

if command -v impressive &> /dev/null; then
    PDF_VIEWER="impressive"
    PDF_VIEWER_CMD="impressive --fullscreen --nooverview --auto $INTERVAL"
    
    if [ "$LOOP" = "true" ]; then
        PDF_VIEWER_CMD="$PDF_VIEWER_CMD --wrap"
    else
        PDF_VIEWER_CMD="$PDF_VIEWER_CMD --autoquit"
    fi
    
    # Impressive handles auto-advance natively, no xdotool needed!
    echo "Using Impressive (built-in auto-advance)..."
    $PDF_VIEWER_CMD "$PDF_FILE"
    exit 0
    
elif command -v evince &> /dev/null; then
    PDF_VIEWER="evince"
    PDF_VIEWER_CMD="evince --presentation"
elif command -v okular &> /dev/null; then
    PDF_VIEWER="okular"
    PDF_VIEWER_CMD="okular --presentation"
else
    echo "Error: No suitable PDF viewer found"
    echo "Install impressive: sudo apt-get install impressive"
    exit 1
fi

echo "Using PDF viewer: $PDF_VIEWER"
echo "Starting presentation mode..."
echo ""

# Start PDF viewer in presentation mode
$PDF_VIEWER_CMD "$PDF_FILE" &
VIEWER_PID=$!

echo "Viewer PID: $VIEWER_PID"
echo "Waiting for viewer to start..."
sleep 5

# Verify it's still running
if ! ps -p $VIEWER_PID > /dev/null 2>&1; then
    echo "Error: PDF viewer exited unexpectedly"
    exit 1
fi

echo "Starting auto-advance..."
echo "Press Ctrl+C to stop"
echo ""

# Auto-advance loop
CURRENT_PAGE=1
MAX_LOOPS=0

if [ "$LOOP" = "false" ]; then
    # Calculate total slides to advance (pages - 1, since we start on page 1)
    MAX_ADVANCES=$((PAGE_COUNT - 1))
else
    # Infinite loop
    MAX_ADVANCES=999999
fi

ADVANCE_COUNT=0

while ps -p $VIEWER_PID > /dev/null 2>&1 && [ $ADVANCE_COUNT -lt $MAX_ADVANCES ]; do
    sleep $INTERVAL
    
    # Find the PDF viewer window
    VIEWER_WINDOW=$(xdotool search --pid $VIEWER_PID 2>/dev/null | tail -1)
    
    if [ -z "$VIEWER_WINDOW" ]; then
        # Fallback: search by window name
        VIEWER_WINDOW=$(xdotool search --name "$(basename "$PDF_FILE")" 2>/dev/null | tail -1)
    fi
    
    if [ -n "$VIEWER_WINDOW" ]; then
        # Ensure window is focused
        xdotool windowactivate --sync "$VIEWER_WINDOW" 2>/dev/null
        sleep 0.2
        
        # Send Right Arrow or Page Down (both work in most PDF viewers)
        xdotool key --clearmodifiers --window "$VIEWER_WINDOW" Right
        
        CURRENT_PAGE=$((CURRENT_PAGE + 1))
        ADVANCE_COUNT=$((ADVANCE_COUNT + 1))
        
        echo "[$(date '+%H:%M:%S')] Advanced to page $CURRENT_PAGE"
        
        # Check if we've reached the end
        if [ $CURRENT_PAGE -gt $PAGE_COUNT ]; then
            if [ "$LOOP" = "true" ]; then
                echo "Reached end, looping back to start..."
                CURRENT_PAGE=1
            else
                echo ""
                echo "Reached end of presentation (page $PAGE_COUNT)"
                echo "Keeping viewer open..."
                # Keep viewer running, just stop advancing
                wait $VIEWER_PID
                exit 0
            fi
        fi
    else
        # Fallback: send key to active window
        xdotool key --clearmodifiers Right
        CURRENT_PAGE=$((CURRENT_PAGE + 1))
        ADVANCE_COUNT=$((ADVANCE_COUNT + 1))
        echo "[$(date '+%H:%M:%S')] Advanced (fallback) #$ADVANCE_COUNT"
    fi
done

echo ""
echo "Presentation ended"
exit 0