#!/bin/bash
set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
BUILD_DIR="$SCRIPT_DIR/ffmpeg_build"
SRC_DIR="$BUILD_DIR/src"
INSTALL_DIR="$BUILD_DIR/install"
JOBS=$(nproc 2>/dev/null || echo 4)

case "$(uname -s)" in
    Linux)                      PLATFORM=linux ;;
    MINGW*|MSYS*|CYGWIN*)       PLATFORM=windows ;;
    *) echo "Unsupported platform: $(uname -s)"; exit 1 ;;
esac

log()  { echo "[FFmpeg] $1"; }
die()  { echo "[FFmpeg] ERROR: $1" >&2; exit 1; }
check_cmd() { command -v "$1" >/dev/null 2>&1 || die "$1 not found. Install it first."; }

do_clone() {
    local name="$1" url="$2" tag="$3"
    if [ ! -d "$SRC_DIR/$name" ]; then
        log "Clone $name..."
        for i in 1 2 3; do
            git clone --depth 1 --branch "$tag" "$url" "$SRC_DIR/$name" 2>&1 && break
            log "Clone attempt $i failed, retrying..."
            rm -rf "$SRC_DIR/$name"
            sleep 2
        done
        [ -d "$SRC_DIR/$name/.git" ] || die "Failed to clone $name after 3 attempts"
    else
        log "Skip clone $name: already exists"
    fi
}

# ============================================================================
# Step 0: System dependencies
# ============================================================================
if [ "$PLATFORM" = "linux" ]; then
    MISSING=""
    for pkg in build-essential cmake nasm pkg-config meson ninja-build git; do
        dpkg -s "$pkg" >/dev/null 2>&1 || MISSING="$MISSING $pkg"
    done
    if [ -n "$MISSING" ]; then
        log "Installing build tools:$MISSING"
        sudo apt update -qq && sudo apt install -y $MISSING
    fi
    HW_DEPS="libva-dev libvdpau-dev"
    for pkg in $HW_DEPS; do
        dpkg -s "$pkg" >/dev/null 2>&1 || { log "Installing $pkg (HW accel)"; sudo apt install -y $pkg; }
    done
else
    check_cmd pacman
    for pkg in mingw-w64-ucrt-x86_64-cmake mingw-w64-ucrt-x86_64-ninja mingw-w64-ucrt-x86_64-nasm \
               mingw-w64-ucrt-x86_64-pkg-config mingw-w64-ucrt-x86_64-meson; do
        pacman -Qi "$pkg" >/dev/null 2>&1 || { log "Installing $pkg"; pacman -S --noconfirm "$pkg"; }
    done
fi

check_cmd cmake
check_cmd nasm
check_cmd pkg-config
check_cmd meson
check_cmd git

# ============================================================================
# Step 1: Codec libraries (static .a, built with -fPIC)
# ============================================================================
mkdir -p "$SRC_DIR" "$INSTALL_DIR/lib/pkgconfig"

export PKG_CONFIG_PATH="$INSTALL_DIR/lib/pkgconfig${PKG_CONFIG_PATH:+:$PKG_CONFIG_PATH}"

# --- x264 (H.264 encoder) ---
if [ ! -f "$INSTALL_DIR/lib/pkgconfig/x264.pc" ]; then
    do_clone x264 https://code.videolan.org/videolan/x264.git stable
    cd "$SRC_DIR/x264"
    log "Configure x264..."
    ./configure --prefix="$INSTALL_DIR" --enable-static --disable-shared \
        --disable-opencl --disable-avs --disable-swscale --disable-lavf \
        --disable-ffms --disable-gpac --disable-lsmash \
        --extra-cflags="-fPIC" --disable-cli
    log "Build x264..."
    make -j"$JOBS"
    make install
    log "x264 OK"
else
    log "Skip x264: already built"
fi

# --- x265 (H.265/HEVC encoder) ---
if [ ! -f "$INSTALL_DIR/lib/pkgconfig/x265.pc" ]; then
    do_clone x265 https://bitbucket.org/multicoreware/x265_git.git master
    cd "$SRC_DIR/x265"
    mkdir -p build && cd build
    log "Configure x265..."
    cmake ../source -G "Unix Makefiles" \
        -DCMAKE_INSTALL_PREFIX="$INSTALL_DIR" \
        -DBUILD_SHARED_LIBS=OFF \
        -DCMAKE_POSITION_INDEPENDENT_CODE=ON \
        -DENABLE_CLI=OFF -DENABLE_SHARED=OFF \
        -DHIGH_BIT_DEPTH=OFF -DENABLE_HDR10_PLUS=OFF
    log "Build x265..."
    cmake --build . -j"$JOBS"
    cmake --install .
    cat > "$INSTALL_DIR/lib/pkgconfig/x265.pc" <<EOF
prefix=$INSTALL_DIR
exec_prefix=\${prefix}
libdir=\${exec_prefix}/lib
includedir=\${prefix}/include

Name: x265
Description: H.265/HEVC video encoder
Version: 4.1
Libs: -L\${libdir} -lx265
Libs.private: -lstdc++ -lm -lpthread
Cflags: -I\${includedir}
EOF
    log "x265 OK"
else
    log "Skip x265: already built"
fi

# --- libvpx (VP8/VP9 encoder) ---
if [ ! -f "$INSTALL_DIR/lib/pkgconfig/vpx.pc" ]; then
    do_clone libvpx https://chromium.googlesource.com/webm/libvpx main
    cd "$SRC_DIR/libvpx"
    log "Configure libvpx..."
    ./configure --prefix="$INSTALL_DIR" --enable-static --disable-shared \
        --enable-pic --enable-vp8 --enable-vp9 --enable-vp9-highbitdepth \
        --disable-examples --disable-tools --disable-docs --disable-unit-tests
    log "Build libvpx..."
    make -j"$JOBS"
    make install
    log "libvpx OK"
else
    log "Skip libvpx: already built"
fi

# --- SVT-AV1 (fast AV1 encoder) ---
if [ ! -f "$INSTALL_DIR/lib/pkgconfig/SvtAv1Enc.pc" ]; then
    do_clone SVT-AV1 https://gitlab.com/AOMediaCodec/SVT-AV1.git v2.3.0
    cd "$SRC_DIR/SVT-AV1"
    mkdir -p build && cd build
    log "Configure SVT-AV1..."
    cmake .. -G "Unix Makefiles" \
        -DCMAKE_INSTALL_PREFIX="$INSTALL_DIR" \
        -DBUILD_SHARED_LIBS=OFF -DBUILD_APPS=OFF \
        -DBUILD_TESTING=OFF -DBUILD_DEC=OFF
    log "Build SVT-AV1..."
    cmake --build . -j"$JOBS"
    cmake --install .
    log "SVT-AV1 OK"
else
    log "Skip SVT-AV1: already built"
fi

# --- libaom (reference AV1 encoder) ---
if [ ! -f "$INSTALL_DIR/lib/pkgconfig/aom.pc" ]; then
    do_clone libaom https://aomedia.googlesource.com/aom v3.12.0
    cd "$SRC_DIR/libaom"
    mkdir -p build && cd build
    log "Configure libaom..."
    cmake .. -G "Unix Makefiles" \
        -DCMAKE_INSTALL_PREFIX="$INSTALL_DIR" \
        -DBUILD_SHARED_LIBS=OFF -DENABLE_TESTS=OFF \
        -DENABLE_TOOLS=OFF -DENABLE_DOCS=OFF \
        -DENABLE_NASM=ON
    log "Build libaom..."
    cmake --build . -j"$JOBS"
    cmake --install .
    log "libaom OK"
else
    log "Skip libaom: already built"
fi

# --- dav1d (fast AV1 decoder) ---
if [ ! -f "$INSTALL_DIR/lib/pkgconfig/dav1d.pc" ]; then
    do_clone dav1d https://code.videolan.org/videolan/dav1d.git 1.5.1
    cd "$SRC_DIR/dav1d"
    log "Configure dav1d..."
    meson setup build --prefix="$INSTALL_DIR" --buildtype release --libdir lib \
        -Ddefault_library=static -Denable_tools=false -Denable_tests=false -Denable_docs=false
    log "Build dav1d..."
    meson compile -C build -j"$JOBS"
    meson install -C build
    log "dav1d OK"
else
    log "Skip dav1d: already built"
fi

# --- nv-codec-headers (NVIDIA NVENC/NVDEC headers, no build needed) ---
if [ ! -f "$INSTALL_DIR/include/ffnvcodec/nvEncodeAPI.h" ]; then
    do_clone nv-codec-headers https://github.com/FFmpeg/nv-codec-headers.git master
    cd "$SRC_DIR/nv-codec-headers"
    log "Install nv-codec-headers..."
    make install PREFIX="$INSTALL_DIR"
    log "nv-codec-headers OK"
else
    log "Skip nv-codec-headers: already installed"
fi

# ============================================================================
# Step 2: FFmpeg
# ============================================================================
if [ -f "$INSTALL_DIR/lib/pkgconfig/libavcodec.pc" ]; then
    log "FFmpeg already built, skipping."
    log "Done: $INSTALL_DIR"
    exit 0
fi

FFMPEG_SRC="$SRC_DIR/ffmpeg"
if [ ! -d "$FFMPEG_SRC" ]; then
    log "Download FFmpeg 7.1.2..."
    FFMPEG_TARBALL="$SRC_DIR/ffmpeg-7.1.2.tar.xz"
    if [ ! -f "$FFMPEG_TARBALL" ]; then
        for url in \
            "https://ffmpeg.org/releases/ffmpeg-7.1.2.tar.xz" \
            "https://github.com/FFmpeg/FFmpeg/archive/refs/tags/n7.1.2.tar.gz"; do
            curl -L --retry 3 -o "$FFMPEG_TARBALL" "$url" 2>&1 && break
            log "Download from $url failed, trying next..."
            rm -f "$FFMPEG_TARBALL"
        done
        [ -f "$FFMPEG_TARBALL" ] || die "Failed to download FFmpeg tarball"
        log "Download OK ($(du -h "$FFMPEG_TARBALL" | cut -f1))"
    fi
    log "Extract FFmpeg..."
    mkdir -p "$FFMPEG_SRC"
    tar -xf "$FFMPEG_TARBALL" -C "$FFMPEG_SRC" --strip-components=1
    rm -f "$FFMPEG_TARBALL"
fi

cd "$SRC_DIR/ffmpeg"
log "Configure FFmpeg..."

CONFIGURE_ARGS=(
    --prefix="$INSTALL_DIR"
    --enable-shared --disable-static
    --enable-gpl --enable-version3
    --pkg-config-flags=--static
    --extra-cflags="-I$INSTALL_DIR/include"
    --extra-ldflags="-L$INSTALL_DIR/lib"
    --extra-libs="-lpthread -lm -ldl"
    --enable-libx264 --enable-libx265
    --enable-libvpx --enable-libsvtav1 --enable-libaom
    --enable-libdav1d
    --enable-nvenc --enable-cuda --enable-cuvid
    --enable-vaapi --enable-vdpau
    --disable-programs --disable-doc --disable-avdevice
    --disable-ffprobe --disable-ffplay --disable-ffmpeg
    --disable-debug --enable-optimizations
)

if [ "$PLATFORM" = "windows" ]; then
    CONFIGURE_ARGS+=(
        --enable-d3d11va --enable-dxva2
    )
fi

"./configure" "${CONFIGURE_ARGS[@]}"

log "Build FFmpeg..."
make -j"$JOBS"
make install

log "==============================================================="
log "FFmpeg build SUCCESS"
log "Install prefix: $INSTALL_DIR"
log "Libraries: $(ls "$INSTALL_DIR/lib/"*.so* "$INSTALL_DIR/lib/"*.dll.a "$INSTALL_DIR/bin/"*.dll 2>/dev/null | tr '\n' ' ')"
log "==============================================================="