#!/bin/bash
# build_pgo.sh - HAKMEM PGO (Profile-Guided Optimization) Build Script
# Usage: ./build_pgo.sh [clean|profile|build|all]
#
# Phase 8.4: Automated PGO build for maximum performance
# Expected: 300-350M ops/sec (vs 200-220M normal build)

set -e  # Exit on error

BENCHMARK="bench_comprehensive_hakmem"
PROFILE_RUN="HAKMEM_WRAP_TINY=1"

# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
NC='\033[0m' # No Color

log() {
    echo -e "${BLUE}[PGO]${NC} $1"
}

success() {
    echo -e "${GREEN}✓${NC} $1"
}

warn() {
    echo -e "${YELLOW}⚠${NC} $1"
}

error() {
    echo -e "${RED}✗${NC} $1"
    exit 1
}

# Step 0: Clean previous builds
clean() {
    log "Cleaning previous builds..."
    make clean > /dev/null 2>&1 || true
    rm -f *.gcda *.o ${BENCHMARK} 2>/dev/null || true
    success "Clean complete"
}

# Step 1: Build with profiling instrumentation
build_instrumented() {
    log "Step 1/3: Building instrumented binary..."

    # Get base flags from Makefile and add PGO instrumentation
    BASE_CFLAGS="-O3 -march=native -mtune=native -Wall -Wextra -std=c11 -D_GNU_SOURCE -D_POSIX_C_SOURCE=199309L -DHAKMEM_DEBUG_TIMING=0 -ffast-math -funroll-loops"
    BASE_LDFLAGS="-lm -lpthread"

    make CFLAGS="$BASE_CFLAGS -fprofile-generate -flto" \
         LDFLAGS="$BASE_LDFLAGS -fprofile-generate -flto" \
         ${BENCHMARK} 2>&1 | tail -5

    if [ ! -f "${BENCHMARK}" ]; then
        error "Instrumented build failed!"
    fi

    success "Instrumented build complete"
}

# Step 2: Collect profile data
collect_profile() {
    log "Step 2/3: Running profile workload..."
    echo -e "${YELLOW}Running benchmark to collect profile data...${NC}"
    # Run with a time budget to ensure exit and profile write-out
    timeout -s INT 20 ${PROFILE_RUN} ./${BENCHMARK} 2>&1 | grep -E "(Test 1:|Throughput:)" | head -6 || true

    # Check if profile data was generated (any .gcda)
    GCDA_COUNT=$(ls -1 *.gcda 2>/dev/null | wc -l || echo 0)
    if [ "${GCDA_COUNT}" -eq 0 ]; then
        error "Profile data not generated!"
    fi

    success "Profile data collected (${GCDA_COUNT} *.gcda files)"
}

# Step 3: Build optimized binary using profile
build_optimized() {
    log "Step 3/3: Building PGO-optimized binary..."

    # Remove old .o files but keep .gcda
    rm -f *.o ${BENCHMARK}

    # Add -Wno-error=coverage-mismatch to avoid PGO warnings
    BASE_CFLAGS="-O3 -march=native -mtune=native -Wall -Wextra -std=c11 -D_GNU_SOURCE -D_POSIX_C_SOURCE=199309L -DHAKMEM_DEBUG_TIMING=0 -ffast-math -funroll-loops"
    BASE_LDFLAGS="-lm -lpthread"

    make CFLAGS="$BASE_CFLAGS -fprofile-use -flto -Wno-error=coverage-mismatch" \
         LDFLAGS="$BASE_LDFLAGS -fprofile-use -flto" \
         ${BENCHMARK} 2>&1 | grep -v "coverage mismatch" | tail -5

    if [ ! -f "${BENCHMARK}" ]; then
        error "PGO-optimized build failed!"
    fi

    success "PGO-optimized build complete"
}

# Quick benchmark to verify performance
quick_bench() {
    log "Running quick performance check..."
    echo ""
    ./${BENCHMARK} 2>&1 | grep -E "(128 B|Throughput:|Long-lived)" | head -10
    echo ""
}

# Main workflow
main() {
    local mode="${1:-all}"

    echo ""
    echo "========================================="
    echo "  HAKMEM PGO Build Script (Phase 8.4)"
    echo "========================================="
    echo ""

    case "$mode" in
        clean)
            clean
            ;;
        profile)
            clean
            build_instrumented
            collect_profile
            ;;
        build)
            if [ ! -f "hakmem_tiny.gcda" ]; then
                error "No profile data found! Run './build_pgo.sh profile' first"
            fi
            build_optimized
            quick_bench
            ;;
        all)
            clean
            build_instrumented
            collect_profile
            build_optimized

            echo ""
            success "PGO build complete! Expected: 300-350M ops/sec"
            warn "Run './bench_comprehensive_hakmem' for full benchmark"
            echo ""
            ;;
        *)
            echo "Usage: $0 [clean|profile|build|all]"
            echo ""
            echo "  clean     - Clean previous builds"
            echo "  profile   - Build instrumented + collect profile"
            echo "  build     - Build optimized using existing profile"
            echo "  all       - Full PGO build (default)"
            echo ""
            exit 1
            ;;
    esac
}

main "$@"