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

# Installs dua (Disk Usage Analyzer) — https://github.com/byron/dua-cli
#
# Supported platforms:
#   macOS    : Apple Silicon (arm64), Intel (x86_64) — via Homebrew
#   Linux    : x86_64, aarch64 — via package manager or direct download
#
# Prerequisites:
#   - macOS: Homebrew (brew) — auto-installed if missing
#   - Linux: curl — for direct download fallback

set -euo pipefail

# ────────────────────────────────────────────
# Constants
# ────────────────────────────────────────────
REPO="Byron/dua-cli"
API_URL="https://api.github.com/repos/${REPO}/releases"
FALLBACK_TAG="v2.46.0"
INSTALL_DIR="${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; }

# ────────────────────────────────────────────
# Ensure Homebrew is available on macOS
# ────────────────────────────────────────────
ensure_brew() {
	if command -v brew &>/dev/null; then
		return 0
	fi
	info "Homebrew is not installed. Installing Homebrew..."
	/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
	if [ -d /opt/homebrew/bin ]; then
		export PATH="/opt/homebrew/bin:$PATH"
	fi
	if [ -d /usr/local/bin ]; then
		export PATH="/usr/local/bin:$PATH"
	fi
	command -v brew &>/dev/null || error "Homebrew installation failed. Install it manually: https://brew.sh/"
	success "Homebrew installed"
}

# ────────────────────────────────────────────
# Detect OS / Architecture
# ────────────────────────────────────────────
OS="$(uname -s)"
ARCH="$(uname -m)"

case "$OS" in
Darwin | Linux) ;;
*)
	error "Unsupported OS: $OS. This script only supports macOS and Linux."
	;;
esac

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

# Fallback: use python3 if jq is not available
# Note: Byron/dua-cli publishes library tags like 'dua-core-v5.0.1' without binary assets.
# Filter only CLI releases whose tag starts with 'v' and contain downloadable assets.
if command -v jq &>/dev/null; then
	_json_latest_tag() {
		jq -r '[.[] | select(.prerelease==false and (.tag_name | startswith("v")) and (.assets | length > 0))] | .[0].tag_name'
	}
elif command -v python3 &>/dev/null; then
	_json_latest_tag() {
		python3 -c "
import sys, json
data = json.load(sys.stdin)
for r in data:
    tag = r.get('tag_name', '')
    if not r.get('prerelease') and tag.startswith('v') and r.get('assets'):
        print(tag)
        break
"
	}
else
	_json_latest_tag() {
		grep -oE '"tag_name":[[:space:]]*"v[0-9]+\.[0-9]+\.[0-9]+"' | head -1 | sed -E 's/.*"v/v/; s/"$//'
	}
fi

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

	local releases=""
	releases="$(curl -fsSL -H "User-Agent: install-dua-sh" "${API_URL}" 2>/dev/null)" || true

	local tag=""
	if [[ -n "$releases" ]]; then
		tag="$(echo "$releases" | _json_latest_tag 2>/dev/null || true)"
	fi

	if [[ -z "$tag" || "$tag" == "null" ]]; then
		warn "Could not fetch latest release tag from GitHub API. Using fallback tag: ${FALLBACK_TAG}"
		tag="${FALLBACK_TAG}"
	fi
	echo "$tag"
}

# ────────────────────────────────────────────
# Install binary from GitHub releases
# ────────────────────────────────────────────
install_from_github() {
	local target=""
	case "$OS" in
	Darwin)
		case "$ARCH" in
		x86_64 | amd64) target="x86_64-apple-darwin" ;;
		aarch64 | arm64) target="aarch64-apple-darwin" ;;
		*) error "Unsupported macOS architecture: $ARCH" ;;
		esac
		;;
	Linux)
		case "$ARCH" in
		x86_64 | amd64) target="x86_64-unknown-linux-musl" ;;
		aarch64 | arm64) target="aarch64-unknown-linux-musl" ;;
		armv7l | armhf) target="arm-unknown-linux-gnueabihf" ;;
		riscv64) target="riscv64gc-unknown-linux-gnu" ;;
		*) error "Unsupported Linux architecture: $ARCH" ;;
		esac
		;;
	esac

	local tag
	tag="$(get_latest_tag)"
	local filename="dua-${tag}-${target}.tar.gz"
	local download_url="https://github.com/${REPO}/releases/download/${tag}/${filename}"

	info "Downloading: $download_url"
	TMPDIR="$(mktemp -d)"
	trap '[[ -d "${TMPDIR:-}" ]] && rm -rf "$TMPDIR"' EXIT

	curl -fsSL --progress-bar -o "${TMPDIR}/${filename}" "$download_url" ||
		error "Download failed: $download_url"

	info "Extracting..."
	tar -xzf "${TMPDIR}/${filename}" -C "$TMPDIR"

	# Find the dua binary
	local dua_bin
	dua_bin="$(find "$TMPDIR" -maxdepth 3 -type f -name "dua" | head -1)"
	[[ -z "$dua_bin" ]] && error "Cannot find 'dua' binary in the archive."

	mkdir -p "$INSTALL_DIR"
	cp "$dua_bin" "${INSTALL_DIR}/dua"
	chmod +x "${INSTALL_DIR}/dua"
	export PATH="${INSTALL_DIR}:${PATH}"
	success "dua ${tag} installed to ${INSTALL_DIR}/dua"

	# PATH instructions
	if ! grep -qs "${INSTALL_DIR}" "${HOME}/.bashrc" "${HOME}/.zshrc" 2>/dev/null; then
		if [[ ":$PATH:" != *":${INSTALL_DIR}:"* ]]; then
			warn "'${INSTALL_DIR}' is not in your PATH."
		fi
		info "Ensure '${INSTALL_DIR}' is in your PATH (e.g. ~/.bashrc or ~/.zshrc):"
		info "  export PATH=\"\$HOME/.local/bin:\$PATH\""
	fi
}

# ────────────────────────────────────────────
# Step 1: Install dua
# ────────────────────────────────────────────
info "Installing dua (Disk Usage Analyzer)..."

if command -v dua &>/dev/null; then
	CURRENT_VER="$(dua --version 2>/dev/null || echo 'unknown')"
	info "dua is already installed ($CURRENT_VER). Updating/checking latest version..."
fi

case "$OS" in
Darwin)
	if command -v brew &>/dev/null && brew install dua-cli 2>/dev/null; then
		success "dua installed via Homebrew"
	else
		info "Installing dua from GitHub releases..."
		install_from_github
	fi
	;;
Linux)
	info "Installing dua from GitHub releases..."
	install_from_github
	;;
esac

# Verify dua is available
if command -v dua &>/dev/null; then
	success "dua is available: $(command -v dua)"
else
	warn "dua was not found in PATH after installation. You may need to open a new terminal."
fi

# ────────────────────────────────────────────
# Step 2: Post-install notes
# ────────────────────────────────────────────
info ""
info "=================================================="
success "dua installation complete!"
info "=================================================="
info ""
info "Getting started:"
info "  dua                     - Show disk usage of current directory"
info "  dua /path/to/dir        - Show disk usage of specific directory"
info "  dua i                   - Interactive mode (explore & delete)"
info "  dua --help              - Show help"
info ""
info "Interactive mode shortcuts:"
info "  Arrow keys / h/j/k/l   - Navigate"
info "  ?                       - Show help"
info "  d                       - Delete selected entry"
info "  q / Esc                 - Quit"