#!/bin/bash
# realm installer
# Usage: curl -fsSL https://raw.githubusercontent.com/yusukeshib/realm/main/install.sh | bash

set -e

REPO="yusukeshib/realm"
INSTALL_DIR="${INSTALL_DIR:-/usr/local/bin}"

detect_platform() {
    local os arch
    os="$(uname -s)"
    arch="$(uname -m)"

    case "$os" in
        Linux)  os="linux" ;;
        Darwin) os="darwin" ;;
        *)
            echo "Error: Unsupported OS: $os" >&2
            return 1
            ;;
    esac

    case "$arch" in
        x86_64|amd64)  arch="x86_64" ;;
        aarch64|arm64) arch="aarch64" ;;
        *)
            echo "Error: Unsupported architecture: $arch" >&2
            return 1
            ;;
    esac

    echo "realm-${arch}-${os}"
}

get_latest_tag() {
    curl -fsSL "https://api.github.com/repos/${REPO}/releases/latest" \
        | grep '"tag_name"' \
        | sed 's/.*"tag_name": *"\([^"]*\)".*/\1/'
}

install_binary() {
    local asset tag url tmpdir
    asset="$(detect_platform)" || return 1
    echo "Detected platform: ${asset}"

    echo "Fetching latest release..."
    tag="$(get_latest_tag)"
    if [ -z "$tag" ]; then
        echo "Error: Could not determine latest release" >&2
        return 1
    fi
    echo "Latest release: ${tag}"

    url="https://github.com/${REPO}/releases/download/${tag}/${asset}"
    tmpdir="$(mktemp -d)"
    trap 'rm -rf "$tmpdir"' EXIT

    echo "Downloading ${url}..."
    if ! curl -fsSL -o "${tmpdir}/realm" "$url"; then
        echo "Binary download failed" >&2
        return 1
    fi

    chmod +x "${tmpdir}/realm"

    if [ -w "$INSTALL_DIR" ]; then
        mv "${tmpdir}/realm" "${INSTALL_DIR}/realm"
    else
        echo "Installing to ${INSTALL_DIR} (requires sudo)..."
        sudo mv "${tmpdir}/realm" "${INSTALL_DIR}/realm"
    fi

    echo "Installed realm to ${INSTALL_DIR}/realm"
}

install_cargo() {
    if ! command -v cargo &>/dev/null; then
        return 1
    fi
    echo "Installing realm via cargo..."
    cargo install realm-cli
}

install_nix() {
    if ! command -v nix &>/dev/null; then
        return 1
    fi
    echo "Installing realm via nix..."
    nix profile install "github:${REPO}"
}

echo "Installing realm..."

if install_binary; then
    echo ""
    echo "Done!"
elif install_cargo; then
    echo ""
    echo "Done! Make sure ~/.cargo/bin is in your PATH:"
    echo "  export PATH=\"\$HOME/.cargo/bin:\$PATH\""
elif install_nix; then
    echo ""
    echo "Done!"
else
    echo ""
    echo "Error: Could not install realm." >&2
    echo "Install one of the following and try again:" >&2
    echo "  - cargo: https://rustup.rs/" >&2
    echo "  - nix:   https://nixos.org/download/" >&2
    exit 1
fi

echo ""
echo "Try it out:"
echo "  cd ~/your-git-repo && realm my-session -c"
echo "  realm my-session -c --image ubuntu:latest -- bash"
echo ""