#!/bin/sh
# Build all user-mode applications as flat binaries.
# Usage: build_apps.sh <apps_dir> <output_dir>
# Each app directory in <apps_dir>/ gets compiled and its flat binary
# is placed in <output_dir>/.
set -e

APPS_DIR="$1"
OUTPUT_DIR="$2"
LINKER_SCRIPT="$APPS_DIR/user.ld"

CC="${CC:-clang}"
OBJCOPY="${OBJCOPY:-objcopy}"
CFLAGS="-ffreestanding -m32 -fno-pie -fno-pic -fno-builtin -fno-stack-protector -mno-sse -mno-mmx -O2 -Wall -I$APPS_DIR/libc"
LDFLAGS="-m32 -nostdlib -no-pie -Wl,--no-dynamic-linker"

mkdir -p "$OUTPUT_DIR"

# Build crt0 if it exists
CRT0_OBJ=""
if [ -f "$APPS_DIR/libc/crt0.S" ]; then
    CRT0_OBJ="$OUTPUT_DIR/_crt0.o"
    $CC $CFLAGS -c "$APPS_DIR/libc/crt0.S" -o "$CRT0_OBJ"
fi

for app_dir in "$APPS_DIR"/*/; do
    [ -d "$app_dir" ] || continue
    app_name=$(basename "$app_dir")
    
    # Skip the libc directory (shared library, not an app)
    [ "$app_name" = "libc" ] && continue

    echo "Building app: $app_name"

    # Collect source files
    OBJ_FILES=""
    for src in "$app_dir"*.S "$app_dir"*.c; do
        [ -f "$src" ] || continue
        obj="$OUTPUT_DIR/${app_name}_$(basename "${src%.*}").o"
        $CC $CFLAGS -c "$src" -o "$obj"
        OBJ_FILES="$OBJ_FILES $obj"
    done

    if [ -z "$OBJ_FILES" ]; then
        echo "  No sources found, skipping"
        continue
    fi

    # Link into ELF (include crt0 if app has .c files and doesn't have its own _start)
    elf="$OUTPUT_DIR/$app_name.elf"
    HAS_C_FILES=""
    for src in "$app_dir"*.c; do
        [ -f "$src" ] && HAS_C_FILES="yes"
    done

    if [ -n "$HAS_C_FILES" ] && [ -n "$CRT0_OBJ" ]; then
        $CC $LDFLAGS -T "$LINKER_SCRIPT" "$CRT0_OBJ" $OBJ_FILES -o "$elf"
    else
        $CC $LDFLAGS -T "$LINKER_SCRIPT" $OBJ_FILES -o "$elf"
    fi

    # Convert to flat binary (include .bss for zero-initialized data)
    bin="$OUTPUT_DIR/$app_name"
    $OBJCOPY -O binary --only-section=.text --only-section=.rodata --only-section=.data --only-section=.bss "$elf" "$bin"

    size=$(wc -c < "$bin")
    echo "  Built: $bin ($size bytes)"
done