#!/bin/bash

# Script to build latest development Mesa for maximum gaming performance on Orange Pi 5 Max
# Optimized for Panfrost with Panthor kernel support, Wayland, X11, and full Vulkan via PanVK
# Installs to /usr, which may overwrite system Mesa—backup your existing /usr/lib/aarch64-linux-gnu/libGL* files first!
# Assumes Debian Bookworm or similar; ensure your kernel has Panthor module enabled (modprobe panthor)

# Exit on any error
set -e

# Define variables
MESADIR="$HOME/Downloads/mesa"
BUILDDIR="$MESADIR/builddir"
INSTALL_PREFIX="/usr/local"
MESA_VERSION="main (development branch)"  # Always uses the dev branch for latest features
CFLAGS="-march=armv8-a -mtune=cortex-a76 -O3 -pipe -flto=$(nproc) -funroll-loops -fomit-frame-pointer -fno-plt"
CXXFLAGS="$CFLAGS"

# Check if Panthor kernel module is available
if ! lsmod | grep -q panthor; then
    echo "Warning: Panthor kernel module not loaded/detected. Ensure your kernel (6.9+) supports it for Mali-G610 GPUs."
    echo "You may need to modprobe panthor or upgrade your kernel. Continuing anyway..."
fi

# Install dependencies
echo "Installing dependencies..."
sudo apt update
sudo apt-get build-dep mesa -y  # Pulls all Mesa build deps including LLVM, libdrm, etc.
sudo apt install -y meson cmake ninja-build pkgconf build-essential gcc g++ libdrm-dev libx11-dev libxext-dev libxrandr-dev libxfixes-dev libwayland-dev libegl-dev libgles2-mesa-dev python3-mako flex bison lm-sensors nvtop glslang-tools
sudo apt --no-install-recommends install -t trixie-backports meson ninja-build -y

# Build and install SPIRV-Tools for latest Vulkan support
echo "Building and installing latest SPIRV-Tools..."
if [ ! -d "SPIRV-Tools" ]; then
    git clone https://github.com/KhronosGroup/SPIRV-Tools.git
fi
cd SPIRV-Tools
git pull
git submodule update --init
cd external
if [ ! -d "spirv-headers" ]; then
    git clone https://github.com/KhronosGroup/SPIRV-Headers.git spirv-headers
fi
cd ..
mkdir -p build
cd build
cmake .. -G Ninja -DCMAKE_BUILD_TYPE=Release
ninja
sudo ninja install
cd ../..

# Clone or update Mesa source
echo "Setting up Mesa source..."
if [ ! -d "$MESADIR" ]; then
    echo "Cloning Mesa repository..."
    mkdir -p ~/Downloads
    cd ~/Downloads
    git clone https://gitlab.freedesktop.org/mesa/mesa.git
    cd "$MESADIR"
else
    echo "Updating existing Mesa repository..."
    cd "$MESADIR"
    git checkout main
    git pull
fi

# No specific version checkout—staying on main for dev branch

# Set compiler flags
echo "Setting performance-optimized compiler flags..."
export CFLAGS="$CFLAGS"
export CXXFLAGS="$CXXFLAGS"

# Configure Mesa with Meson
echo "Configuring Mesa with Meson..."
if [ -d "$BUILDDIR" ]; then
    echo "Cleaning existing build directory..."
    rm -rf "$BUILDDIR"
fi
mkdir -p "$BUILDDIR"
cd "$MESADIR"
meson setup builddir \
  -Dprefix="$INSTALL_PREFIX" \
  -Dgallium-drivers=panfrost \
  -Dvulkan-drivers=panfrost \
  -Dplatforms=wayland,x11 \
  -Dbuildtype=release \
  -Dgles1=disabled \
  -Dgles2=enabled \
  -Dllvm=enabled \
  -Db_ndebug=true \
  -Db_lto=true \
  -Db_lto_threads=$(nproc) \
  -Dc_args="$CFLAGS" \
  -Dcpp_args="$CXXFLAGS"

# Compile Mesa
echo "Compiling Mesa..."
ninja -C builddir -j$(nproc)

# Install Mesa
echo "Installing Mesa to $INSTALL_PREFIX..."
echo "Warning: This will overwrite system Mesa libraries in /usr. Ensure you've backed up if needed."
sudo ninja -C builddir install

# Completion message with runtime tips
echo "Mesa build and installation complete!"
echo "Development Mesa ($MESA_VERSION) installed to $INSTALL_PREFIX. Note: This may have overwritten your system Mesa—test carefully."
echo "Test with: glxgears (X11), es2gears_wayland (Wayland), or vkcube (Vulkan)"
echo "Compiler flags used: $CFLAGS"
echo "For maximum game performance, run:"
echo "  PAN_MESA_DEBUG=perf,gofaster,no_crc MESA_GLSL_CACHE_DISABLE=0 ./your_game"
echo "Set MESA_GLSL_CACHE_DIR=/path/to/fast/storage for faster shader caching."
echo "Monitor temperatures with 'sensors' to avoid thermal throttling."
echo "If Vulkan issues arise, ensure SPIRV-Tools and glslang are properly installed and your kernel uses Panthor."