#!/bin/bash

# Shader compilation script for Vulkan
# Sets up environment and compiles GLSL shaders to SPIR-V

SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
SHADERS_DIR="$SCRIPT_DIR/shaders"
OUTPUT_DIR="$SCRIPT_DIR/src/shaders_spirv"

# Find glslang compiler
GLSLANG=""

# Check custom paths first
if [ -x "$HOME/VulkanSDK/1.4.328.1/macOS/bin/glslang" ]; then
    GLSLANG="$HOME/VulkanSDK/1.4.328.1/macOS/bin/glslang"
    echo "Found glslang at: $GLSLANG"
elif [ -x "$HOME/VulkanSDK/1.4.328.1/macOS/bin/glslangValidator" ]; then
    GLSLANG="$HOME/VulkanSDK/1.4.328.1/macOS/bin/glslangValidator"
    echo "Found glslangValidator at: $GLSLANG"
elif command -v glslc &> /dev/null; then
    GLSLANG="glslc"
    echo "Using system glslc"
elif command -v glslangValidator &> /dev/null; then
    GLSLANG="glslangValidator"
    echo "Using system glslangValidator"
elif command -v glslang &> /dev/null; then
    GLSLANG="glslang"
    echo "Using system glslang"
else
    echo "ERROR: No GLSL compiler found!"
    echo "Please install:"
    echo "  - Vulkan SDK (provides glslc)"
    echo "  - or glslang to ~/VulkanSDK/1.4.328.1/macOS/bin/"
    exit 1
fi

# Create output directory
mkdir -p "$OUTPUT_DIR"

# Compilation function
compile_shader() {
    local shader_file="$1"
    local output_name="$2"
    local spirv_file="$OUTPUT_DIR/${shader_file}.spv"
    local inc_file="$OUTPUT_DIR/${output_name}"

    echo "Compiling $shader_file..."

    # Determine compiler command
    if [[ "$GLSLANG" == *"glslc"* ]]; then
        "$GLSLANG" "$SHADERS_DIR/$shader_file" -o "$spirv_file"
    else
        "$GLSLANG" -V "$SHADERS_DIR/$shader_file" -o "$spirv_file"
    fi

    if [ $? -ne 0 ]; then
        echo "  FAILED to compile $shader_file"
        return 1
    fi

    echo "  SUCCESS - Generated $spirv_file"

    # Generate C++ include file
    echo "  Generating $inc_file..."
    generate_include "$spirv_file" "$inc_file"

    return 0
}

# Generate C++ include file from SPIR-V
generate_include() {
    local spirv_file="$1"
    local inc_file="$2"

    # Use Python if available for better formatting
    if command -v python3 &> /dev/null; then
        python3 -c "
import struct
import sys

with open('$spirv_file', 'rb') as f:
    data = f.read()

num_words = len(data) // 4
words = struct.unpack('<{}I'.format(num_words), data[:num_words*4])

print('// Auto-generated from $(basename $spirv_file)')
print('// Size: {} bytes ({} words)'.format(len(data), num_words))

for i in range(0, num_words, 8):
    chunk = words[i:i+8]
    if i == 0:
        sys.stdout.write('    ')
    else:
        sys.stdout.write(',\n    ')
    sys.stdout.write(', '.join('0x{:08x}u'.format(w) for w in chunk))
print()
" > "$inc_file"
    else
        # Fallback: simple hexdump
        echo "// Auto-generated from $(basename $spirv_file)" > "$inc_file"
        xxd -i < "$spirv_file" | sed 's/unsigned char/uint32_t/' >> "$inc_file"
    fi

    echo "    Generated $inc_file"
}

echo "========================================"
echo "Compiling Vulkan Shaders"
echo "========================================"
echo "Shaders directory: $SHADERS_DIR"
echo "Output directory: $OUTPUT_DIR"
echo "Compiler: $GLSLANG"
echo "========================================"
echo ""

# Compile all shaders
SUCCESS=0
FAILED=0

# Background shaders
if compile_shader "background.vert" "background_vert.inc"; then
    ((SUCCESS++))
else
    ((FAILED++))
fi

if compile_shader "background.frag" "background_frag.inc"; then
    ((SUCCESS++))
else
    ((FAILED++))
fi

# Geometry shaders
if compile_shader "geometry.vert" "geometry_vert.inc"; then
    ((SUCCESS++))
else
    ((FAILED++))
fi

if compile_shader "geometry.frag" "geometry_frag.inc"; then
    ((SUCCESS++))
else
    ((FAILED++))
fi

# Text shaders
if compile_shader "text.vert" "text_vert.inc"; then
    ((SUCCESS++))
else
    ((FAILED++))
fi

if compile_shader "text.frag" "text_frag.inc"; then
    ((SUCCESS++))
else
    ((FAILED++))
fi

echo ""
echo "========================================"
echo "Compilation Summary"
echo "========================================"
echo "Success: $SUCCESS"
echo "Failed: $FAILED"
echo "========================================"

if [ $FAILED -gt 0 ]; then
    exit 1
fi

echo ""
echo "All shaders compiled successfully!"
exit 0