#!/usr/bin/env bash
set -euo pipefail

VERSION=${VERSION:-${1:?Provide VERSION env or arg, e.g. VERSION=0.3.2 bash grokkit-install.sh}}

# Strip leading 'v' if present (makes invocation flexible)
VERSION=${VERSION#v}

GITEA_BASE=https://repos.gmgauthier.com/gmgauthier/grokkit

# Platform detection
OS=$(uname -s | tr '[:upper:]' '[:lower:]')
case "$OS" in
    linux) OS=linux ;;
    darwin) OS=darwin ;;
esac

ARCH=$(uname -m)
case "$ARCH" in
    x86_64|amd64) ARCH=amd64 ;;
    arm64|aarch64) ARCH=arm64 ;;
esac

ASSET="grokkit-${OS}-${ARCH}-v${VERSION}.tar.gz"

echo "Installing grokkit ${VERSION} for ${OS}/${ARCH}..."

TEMP_DIR=$(mktemp -d)
trap 'rm -rf "${TEMP_DIR}"' EXIT

cd "${TEMP_DIR}"

# Download asset + checksums
echo "Downloading ${ASSET}..."
curl -fL "${GITEA_BASE}/releases/download/v${VERSION}/${ASSET}" -o asset.tar.gz

echo "Downloading checksums.txt..."
curl -fL "${GITEA_BASE}/releases/download/v${VERSION}/checksums.txt" -o checksums.txt

# Robust checksum verification
echo "Verifying checksum..."
CHECKSUM_CMD=""
if command -v sha256sum >/dev/null 2>&1; then
    CHECKSUM_CMD="sha256sum"
elif command -v shasum >/dev/null 2>&1; then
    CHECKSUM_CMD="shasum -a 256"
fi

if [ -n "$CHECKSUM_CMD" ] && [ -f checksums.txt ]; then
    # Extract hash (handles "build/..." prefix in checksums.txt)
    HASH=$(grep -oE '[0-9a-f]{64}\s+build/[^ ]*' checksums.txt | grep "${ASSET}" | cut -d' ' -f1)
    if [ -z "$HASH" ]; then
        echo "⚠️  No checksum entry found for ${ASSET} – continuing without verification"
    else
        echo "${HASH}  asset.tar.gz" | $CHECKSUM_CMD --check - || {
            echo "❌ Checksum mismatch for ${ASSET}!"
            exit 1
        }
        echo "✅ Checksum verified successfully"
    fi
else
    echo "⚠️  Checksum tool not found (sha256sum/shasum) – skipping verification"
fi

# Extract
echo "Extracting asset..."
tar xzf asset.tar.gz
BINARY="grokkit-${OS}-${ARCH}"

# Install
INSTALL_DIR="${HOME}/.local/bin"
mkdir -p "${INSTALL_DIR}"
mv "${BINARY}" "${INSTALL_DIR}/grokkit"
chmod +x "${INSTALL_DIR}/grokkit"

echo "✅ grokkit ${VERSION} installed to ${INSTALL_DIR}/grokkit"
echo "Add to PATH if needed: export PATH=\"${INSTALL_DIR}:\$PATH\""
grokkit version