#!/bin/bash

set -e

if [ -z "${CROSSCC_i686}" ]; then
    CROSSCC_i686=i686-elf-gcc
fi

if [ -z "${CROSSAS_i686}" ]; then
    CROSSAS_i686=i686-elf-as
fi

if [ -z "${CROSSCC_x8664}" ]; then
    CROSSCC_x8664=x86_64-elf-gcc
fi

if [ -z "${CROSSAS_x8664}" ]; then
    CROSSAS_x8664=x86_64-elf-as
fi

if [ -z "${CROSSLD_i686}" ]; then
    CROSSLD_i686=i686-elf-ld
fi

if [ -z "${CROSSLD_x8664}" ]; then
    CROSSLD_x8664=x86_64-elf-ld
fi

if [ -z "${STAGE1_DIR}" ]; then
    STAGE1_DIR="./stage1/"
fi

if [ -z "${STAGE2_DIR}" ]; then
    STAGE2_DIR="$(pwd)/stage2"
fi

if [ -z "${BUILD_DIR}" ]; then
    BUILD_DIR="$(pwd)/build"
fi
mkdir -p "${BUILD_DIR}"

if [ -z "${TARGET}" ]; then
    TARGET="$(pwd)/bootloader"
fi

GLOBAL_CFLAGS=(-I./include -ffreestanding -m32 -nostdlib)

LINKER_LD="linker.ld"

# Stage 1

STAGE1_LD="${STAGE1_DIR}/linker.ld"

STAGE1_C_FILES=$(find "${STAGE1_DIR}" -name "*.c")
STAGE1_AS_FILES=$(find "${STAGE1_DIR}" -name "*.S")

STAGE1_AS_TARGET="${BUILD_DIR}/stage1_as.o"
STAGE1_CC_TARGET="${BUILD_DIR}/stage1_cc.o"

STAGE1_TARGET="${BUILD_DIR}/stage1.bin"

# Stage 2

STAGE2_LD="${STAGE1_DIR}/linker.ld"

STAGE2_C_FILES=$(find "${STAGE2_DIR}" -name "*.c")
STAGE2_AS_FILES=$(find "${STAGE2_DIR}" -name "*.S")

STAGE2_AS_TARGET="${BUILD_DIR}/stage2_as.o"
STAGE2_CC_TARGET="${BUILD_DIR}/stage2_cc.o"

STAGE1_DIR="$(pwd)/stage1"
STAGE2_DIR="$(pwd)/stage2"

function usage {
    echo -e "Custom build system."
    echo -e "Available commands:"
    echo -e "    ${0} all"
    echo -e "    ${0} run"
    echo -e "    ${0} build_drive"
    echo -e "    ${0} clean"
    echo -e "    ${0} stage1"
}

function build_lib {
	macro="$1"

	set -e

	local lib_cfiles=$(find "./lib/" -name "*.c")

	mkdir -p "${BUILD_DIR}/lib"
	for i in ${lib_cfiles[@]}; do
		"${CROSSCC_i686}" -m32 -c "$i" "${GLOBAL_CFLAGS[@]}" -o "${BUILD_DIR}/${i}.o" -D${macro}
		echo -e "    [CC] ${i}"
	done

	echo "[LIB] Compiled libraries."
}

function stage1 {
    set -e

    if [[ -e "${BUILD_DIR}/${STAGE1_DIR}" ]] && [[ -f "${BUILD_DIR}/${STAGE1_DIR}" ]]; then
	mkdir -p "${BUILD_DIR}/${STAGE1_DIR}"
	echo -e "Creating the stage 1 build directory ${BUILD_DIR}/${STAGE1_DIR}"
    fi

    echo -e "Producing stage 1 binaries..."

    if [[ ${#STAGE1_AS_FILES[@]} -gt 0 ]] && [[ -n "${STAGE1_AS_FILES[@]}" ]]; then
	echo -e "[STAGE1] Found assembly files: "
	for i in ${STAGE1_AS_FILES[@]}; do
		mkdir -p "${BUILD_DIR}/${i}"
		"${CROSSAS_i686}" "$i" -o "${BUILD_DIR}/${i}.o" 
	    	echo -e "    [AS]: $i"
	done
	echo -e "    [AS] Assembled stage 1."
    else
	echo -e "[STAGE1] No assembly files were found."
    fi

    if [[ ${#STAGE1_C_FILES[@]} -gt 0 ]] && [[ -n "${STAGE1_C_FILES[@]}" ]]; then
	echo -e "[STAGE1] Found C files: "
	for i in ${STAGE1_C_FILES[@]}; do
		"${CROSSCC_i686}" -c "$i" -o "${BUILD_DIR}/${i}.o" "${GLOBAL_CFLAGS[@]}"
		echo -e "    [CC]: $i"
	done
	echo -e "    [CC] Compiled stage 1."
    else
	echo -e "[STAGE1] No C files were found."
    fi

    if [[ ${#STAGE1_C_FILES[@]} -eq 0 ]] && [[ ${#STAGE1_AS_FILES[@]} -eq 0 ]]; then
	echo -e "[STAGE1] No stage1 files were found!"
	exit 1
    fi

    echo -e "Stage 1 binaries completed."
}

function stage2 {
    if [[ -e "${BUILD_DIR}/${STAGE1_DIR}" ]] && [[ -f "${BUILD_DIR}/${STAGE1_DIR}" ]]; then
	mkdir -p "${BUILD_DIR}/${STAGE1_DIR}"
    fi

    ${CROSSAS_i686} "${STAGE2_AS_FILES}" -o "${STAGE2_AS_TARGET}"
    echo -e "    [AS] Assembled stage 2."
    ${CROSSCC_x8664} "${STAGE2_C_FILES}" -o "${STAGE2_CC_TARGET}"
    echo -e "    [CC] Compiled stage 2."
}

function link {
	set -e

	local linker_files=()

	echo -e "[LINK] Linking files..."

	for i in $(find "${BUILD_DIR}" -name "*.o"); do
		linker_files+=("$i")
		echo -e "    [L] Added: $i"
	done

	"${CROSSLD_i686}" -T "${LINKER_LD}" "${linker_files[@]}" -o "${STAGE1_TARGET}"

	echo -e "[LINK] Linking complete."
}

function clean {
	if [[ -e "${BUILD_DIR}" && -d "${BUILD_DIR}" ]]; then
		echo -e "[CLEAN] Deleting build/ directory..."
		rm -rf "${BUILD_DIR}"
	fi
   
	if [[ -e "$(pwd)/disk.img" && -f "$(pwd)/disk.img"  ]]; then
		echo -e "[CLEAN] Deleting disk.img..."
		rm "$(pwd)/disk.img"
	fi
	echo -e "[CLEAN] Project cleaned."
}

function build_image {
	dd if="${STAGE1_TARGET}" of="$(pwd)/disk.img" bs=512 count=15
}

function run {
	qemu-system-x86_64 -drive format=raw,file="$(pwd)/disk.img"
}

function debug {
	qemu-system-x86_64 -drive format=raw,file="$(pwd)/disk.img" -S -s
}

function compile {
    echo "[COMPILE] Compiling and preparing the entire build."
    clean
    mkdir -p ./build/
    build_lib "STAGE1"
    stage1
    link
    build_image
    echo "[COMPILE] DONE"
}

function run {
    qemu-system-x86_64 -drive format=raw,file=disk.img
}

case "$1" in
    "all") compile ;;
    "run") compile && run ;;
    "debug") compile && debug ;;
    "stage1") stage1 ;;
    "build_drive") build_image ;;
    "clean") clean ;;
    "help"|"usage")
	usage
	exit 0
	;;
    "")
	echo -e "You must specify a command."
	echo -e "Type '${0} usage' or '${0} help' for more information."
	exit 1
	;;
    *)
	echo -e "Command not found: '${1}'"
	usage
	exit 1
	;;
esac