#!/usr/bin/env bash
# build-targets.sh — Build the El VM (elvm) for all supported platforms.
#
# Usage:
#   ./build-targets.sh                    # build all targets
#   ./build-targets.sh --list             # list targets and prerequisites
#   ./build-targets.sh x86_64-apple-darwin  # build a specific target
#
# Prerequisites:
#   - Rust toolchain (rustup) with cross-compilation targets installed
#   - For Linux targets: cross-linkers (see comments below)
#
# Install a target:
#   rustup target add <target>
#
# For cross-compilation from macOS to Linux:
#   brew install FiloSottile/musl-cross/musl-cross
#   # or use `cross` (https://github.com/cross-rs/cross):
#   cargo install cross --git https://github.com/cross-rs/cross

set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
OUTPUT_DIR="${SCRIPT_DIR}/dist/elvm"

# ── Target definitions ────────────────────────────────────────────────────────
# Format: "target:description:linker_hint"
declare -a TARGETS=(
    "x86_64-unknown-linux-gnu:Linux x86_64 (glibc):brew install FiloSottile/musl-cross/musl-cross or use 'cross'"
    "aarch64-unknown-linux-gnu:Linux ARM64 (glibc):brew install FiloSottile/musl-cross/musl-cross or use 'cross'"
    "x86_64-unknown-linux-musl:Linux x86_64 (musl, static):brew install FiloSottile/musl-cross/musl-cross"
    "aarch64-unknown-linux-musl:Linux ARM64 (musl, static):brew install aarch64-unknown-linux-musl cross-linker"
    "x86_64-apple-darwin:macOS Intel:native (no cross tooling needed on macOS)"
    "aarch64-apple-darwin:macOS Apple Silicon:native (no cross tooling needed on macOS)"
    "x86_64-pc-windows-gnu:Windows x86_64:brew install mingw-w64"
    "aarch64-pc-windows-msvc:Windows ARM64:requires Windows MSVC SDK (Windows only)"
)

# ── Helpers ───────────────────────────────────────────────────────────────────

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

ok()   { echo -e "  ${GREEN}✓${NC} $*"; }
warn() { echo -e "  ${YELLOW}⚠${NC} $*"; }
fail() { echo -e "  ${RED}✗${NC} $*"; }

# ── List mode ─────────────────────────────────────────────────────────────────

if [[ "${1:-}" == "--list" ]]; then
    echo ""
    echo "El VM cross-compilation targets"
    echo "================================"
    echo ""
    for entry in "${TARGETS[@]}"; do
        IFS=':' read -r target desc hint <<< "$entry"
        printf "  %-42s %s\n" "$target" "$desc"
        printf "  %-42s Prereq: %s\n" "" "$hint"
        echo ""
    done
    echo "Install a target: rustup target add <target>"
    echo "List installed:   rustup target list --installed"
    exit 0
fi

# ── Filter targets ────────────────────────────────────────────────────────────

if [[ $# -gt 0 && "${1:-}" != "--list" ]]; then
    # Build only the specified target(s).
    SELECTED=("$@")
else
    # Build all targets.
    SELECTED=()
    for entry in "${TARGETS[@]}"; do
        IFS=':' read -r target _ _ <<< "$entry"
        SELECTED+=("$target")
    done
fi

# ── Build ─────────────────────────────────────────────────────────────────────

echo ""
echo -e "${BLUE}El VM — cross-platform build${NC}"
echo "Output directory: $OUTPUT_DIR"
echo ""

mkdir -p "$OUTPUT_DIR"

BUILT=0
SKIPPED=0
FAILED=0

for target in "${SELECTED[@]}"; do
    # Find description for this target.
    desc="$target"
    for entry in "${TARGETS[@]}"; do
        IFS=':' read -r t d _ <<< "$entry"
        if [[ "$t" == "$target" ]]; then desc="$d"; break; fi
    done

    echo -e "${BLUE}→ Building $target${NC} ($desc)"

    # Check if the Rust target is installed.
    if ! rustup target list --installed 2>/dev/null | grep -q "^$target\b"; then
        warn "Target $target not installed — installing..."
        if rustup target add "$target" 2>/dev/null; then
            ok "Installed $target"
        else
            fail "Cannot install $target — skipping"
            ((SKIPPED++))
            continue
        fi
    fi

    # Attempt to build.
    binary_suffix=""
    if [[ "$target" == *"windows"* ]]; then
        binary_suffix=".exe"
    fi

    binary_name="elvm-${target}${binary_suffix}"
    output_path="$OUTPUT_DIR/$binary_name"

    if (cd "$SCRIPT_DIR" && cargo build --release --target "$target" -p elvm 2>&1 | tail -5); then
        src="$SCRIPT_DIR/target/$target/release/elvm${binary_suffix}"
        if [[ -f "$src" ]]; then
            cp "$src" "$output_path"
            size=$(du -h "$output_path" | cut -f1)
            ok "Built $binary_name ($size)"
            ((BUILT++))
        else
            fail "Binary not found at $src"
            ((FAILED++))
        fi
    else
        fail "Build failed for $target (cross-linker may be missing — see --list)"
        ((FAILED++))
    fi
    echo ""
done

# ── Summary ───────────────────────────────────────────────────────────────────

echo "────────────────────────────────"
echo "Built:   $BUILT"
echo "Skipped: $SKIPPED"
echo "Failed:  $FAILED"

if [[ $BUILT -gt 0 ]]; then
    echo ""
    echo "Artifacts:"
    ls -lh "$OUTPUT_DIR/"
fi

echo ""
if [[ $FAILED -gt 0 ]]; then
    echo -e "${YELLOW}Some targets failed. Run './build-targets.sh --list' for prerequisites.${NC}"
    exit 1
fi