#!/usr/bin/env bash
# shellcheck disable=SC2086

# Downloads and installs the latest ctop (container terminal UI) from
# https://github.com/bcicen/ctop/releases
#
# Supported platforms:
#   macOS    : Intel (x86_64), Apple Silicon via Rosetta 2 (arm64)
#   Linux    : x86_64 (amd64), aarch64/arm64, arm, ppc64le
#   Windows  : Not supported — use install-ctop.ps1 (PowerShell)

set -euo pipefail

# ────────────────────────────────────────────
# Constants
# ────────────────────────────────────────────
REPO="bcicen/ctop"
API_URL="https://api.github.com/repos/${REPO}/releases"
INSTALL_DIR="${HOME}/.local/bin"

# ────────────────────────────────────────────
# Utility functions (all stderr output)
# ────────────────────────────────────────────
info()    { echo "[INFO]  $*" >&2; }
warn()    { echo "[WARN]  $*" >&2; }
error()   { echo "[ERROR] $*" >&2; exit 1; }
success() { echo "[OK]    $*" >&2; }

# ────────────────────────────────────────────
# Check required commands
# ────────────────────────────────────────────
for cmd in curl uname; do
    command -v "$cmd" &>/dev/null || error "'$cmd' command is required."
done

# Fallback: use python3 if jq is not available
if command -v jq &>/dev/null; then
    _json_latest_tag() {
        jq -r '[.[] | select(.prerelease==false)] | .[0].tag_name'
    }
else
    command -v python3 &>/dev/null || error "'jq' or 'python3' is required."
    _json_latest_tag() {
        python3 -c "
import sys, json
data = json.load(sys.stdin)
for r in data:
    if not r.get('prerelease'):
        print(r['tag_name'])
        break
"
    }
fi

# ────────────────────────────────────────────
# OS / Architecture detection
# ────────────────────────────────────────────
# Returns: "<os>-<arch>" matching ctop's GitHub release asset naming
detect_platform() {
    local os arch

    os="$(uname -s)"
    arch="$(uname -m)"

    case "$os" in
        # ── macOS ──────────────────────────────────────────────
        Darwin)
            case "$arch" in
                x86_64)
                    echo "darwin-amd64"
                    ;;
                arm64)
                    # ctop does not provide a native darwin-arm64 binary.
                    # Use the amd64 binary via Rosetta 2 (works on Apple Silicon).
                    if [[ "$(sysctl -n sysctl.proc_translated 2>/dev/null || echo 0)" == "1" ]] \
                        || command -v arch &>/dev/null; then
                        warn "ctop has no native Apple Silicon build."
                        warn "Using amd64 binary via Rosetta 2."
                        echo "darwin-amd64"
                    else
                        error "No native Apple Silicon build available and Rosetta 2 is not installed." \
                              "Install Rosetta 2: softwareupdate --install-rosetta"
                    fi
                    ;;
                *)
                    error "Unsupported macOS architecture: $arch"
                    ;;
            esac
            ;;

        # ── Linux ──────────────────────────────────────────────
        Linux)
            case "$arch" in
                x86_64|amd64)  echo "linux-amd64"  ;;
                aarch64|arm64) echo "linux-arm64"  ;;
                armv7l|armhf)  echo "linux-arm"    ;;
                ppc64le)       echo "linux-ppc64le" ;;
                *)
                    error "Unsupported Linux architecture: $arch"
                    ;;
            esac
            ;;

        # ── Windows (Git Bash / MSYS2 / Cygwin) ───────────────
        MINGW*|MSYS*|CYGWIN*)
            error "Windows is not supported by this script. Use install-ctop.ps1 instead."
            ;;

        *)
            error "Unsupported OS: $os  (uname -a: $(uname -a))"
            ;;
    esac
}

# ────────────────────────────────────────────
# Get latest stable release tag
# ────────────────────────────────────────────
get_latest_tag() {
    info "Fetching latest release from GitHub API..."

    local releases
    releases="$(curl -fsSL "${API_URL}")" || error "Failed to call GitHub API."

    local tag
    tag="$(echo "$releases" | _json_latest_tag)"

    [[ -z "$tag" || "$tag" == "null" ]] && error "Could not find latest release tag."
    echo "$tag"
}

# ────────────────────────────────────────────
# Build download URL
# ────────────────────────────────────────────
# ctop release assets follow the pattern: ctop-{version}-{os}-{arch}
# where {version} has the 'v' prefix stripped from the git tag.
build_download_url() {
    local tag="$1"
    local platform="$2"   # e.g. darwin-amd64, linux-amd64
    local version="${tag#v}"  # Remove 'v' prefix (v0.7.7 → 0.7.7)
    local filename="ctop-${version}-${platform}"
    echo "https://github.com/${REPO}/releases/download/${tag}/${filename}"
}

# ────────────────────────────────────────────
# Download & install (raw binary — no archive extraction needed)
# ────────────────────────────────────────────
download_and_install() {
    local url="$1"

    local tmpdir
    tmpdir="$(mktemp -d)"
    trap '[[ -d "${tmpdir:-}" ]] && rm -rf "$tmpdir"' EXIT

    local filename
    filename="${url##*/}"

    info "Downloading: $url"
    curl -fsSL --progress-bar -o "${tmpdir}/${filename}" "$url" \
        || error "Download failed: $url"

    # ctop provides raw binaries (not archives), so skip extraction
    local bin_src="${tmpdir}/${filename}"

    # Create install directory
    mkdir -p "$INSTALL_DIR"

    local install_path="${INSTALL_DIR}/ctop"
    info "Installing: ${install_path}"
    cp "$bin_src" "$install_path"
    chmod +x "$install_path"

    success "Installation complete!"
    info "Version check:"
    "$install_path" -v || true

    # PATH instructions
    if ! echo ":${PATH}:" | grep -q ":${INSTALL_DIR}:"; then
        warn "'${INSTALL_DIR}' is not in your PATH."
        warn "Add this line to your ~/.bashrc or ~/.zshrc:"
        warn "  export PATH=\"\$HOME/.local/bin:\$PATH\""
    fi
}

# ────────────────────────────────────────────
# Main
# ────────────────────────────────────────────
main() {
    local platform tag url

    platform="$(detect_platform)"
    info "Detected platform: $platform"

    tag="$(get_latest_tag)"
    info "Latest release: $tag"

    url="$(build_download_url "$tag" "$platform")"
    download_and_install "$url"
}

main "$@"