#!/bin/bash

#
# download-tea.sh - Downloads and installs the Gitea Tea CLI tool for Linux
#
# SYNOPSIS
#     ./download-tea.sh [OPTIONS]
#
# DESCRIPTION
#     This script automatically downloads, verifies, and installs the Tea CLI (Gitea command-line tool).
#     It supports automatic detection of the latest version, SHA256 checksum verification, and intelligent
#     installation location based on user privileges.
#
# OPTIONS
#     -v, --version VERSION    Specifies the version of Tea to install. If not provided, the script will
#                             automatically fetch the latest version from the Gitea releases page.
#     -f, --force             Bypasses the overwrite confirmation prompt if Tea is already installed.
#     -h, --help              Display this help message and exit.
#
# EXAMPLES
#     ./download-tea.sh
#         Automatically detects and installs the latest version of Tea.
#
#     ./download-tea.sh -v 0.11.1
#         Installs a specific version of Tea (v0.11.1).
#
#     ./download-tea.sh --force
#         Installs the latest version and overwrites any existing installation without prompting.
#
#     ./download-tea.sh -v 0.11.1 -f
#         Installs version 0.11.1 and overwrites existing installation without prompting.
#
# NOTES
#     - Requires internet connection to download from https://gitea.com
#     - Automatically detects system architecture (amd64, arm64, 386, arm)
#     - Installation location:
#       * With root/sudo privileges: /usr/local/bin
#       * Without privileges: ~/.local/bin
#     - Automatically updates PATH environment variable if needed
#     - After installation, restart your terminal or reload shell configuration
#
# LINK
#     https://gitea.com/gitea/tea
#

# Color codes for output
readonly GREEN='\033[0;32m'
readonly RED='\033[0;31m'
readonly YELLOW='\033[1;33m'
readonly CYAN='\033[0;36m'
readonly GRAY='\033[0;37m'
readonly NC='\033[0m' # No Color

# Variables
TEA_VERSION=""
FORCE=false

# Show usage information
show_usage() {
    sed -n '3,37p' "$0" | sed 's/^# \?//'
    exit 0
}

# Parse command line arguments
while [[ $# -gt 0 ]]; do
    case $1 in
        -v|--version)
            TEA_VERSION="$2"
            shift 2
            ;;
        -f|--force)
            FORCE=true
            shift
            ;;
        -h|--help)
            show_usage
            ;;
        *)
            echo -e "${RED}Error: Unknown option: $1${NC}" >&2
            echo "Use -h or --help for usage information."
            exit 1
            ;;
    esac
done

# 1. Determine version to install
if [[ -z "$TEA_VERSION" ]]; then
    echo "No version specified. Fetching latest release..."
    
    # Try to fetch the latest version using curl
    if command -v curl &> /dev/null; then
        RELEASE_PAGE=$(curl -sL "https://gitea.com/gitea/tea/releases" 2>&1)
        if [[ $? -ne 0 ]]; then
            echo -e "${RED}Error: Failed to fetch latest version: $RELEASE_PAGE${NC}" >&2
            echo "Please specify a version manually using -v parameter."
            exit 1
        fi
    # Fallback to wget if curl is not available
    elif command -v wget &> /dev/null; then
        RELEASE_PAGE=$(wget -qO- "https://gitea.com/gitea/tea/releases" 2>&1)
        if [[ $? -ne 0 ]]; then
            echo -e "${RED}Error: Failed to fetch latest version: $RELEASE_PAGE${NC}" >&2
            echo "Please specify a version manually using -v parameter."
            exit 1
        fi
    else
        echo -e "${RED}Error: Neither curl nor wget is available${NC}" >&2
        echo "Please install curl or wget, or specify a version manually using -v parameter."
        exit 1
    fi
    
    # Parse the HTML to find the latest version tag (format: /gitea/tea/releases/tag/v0.x.x)
    if [[ "$RELEASE_PAGE" =~ /gitea/tea/releases/tag/v([0-9]+\.[0-9]+\.[0-9]+) ]]; then
        TEA_VERSION="${BASH_REMATCH[1]}"
        echo -e "${GREEN}Latest version found: v$TEA_VERSION${NC}"
    else
        echo -e "${RED}Error: Could not determine the latest version from the releases page.${NC}" >&2
        echo "Please specify a version manually using -v parameter."
        exit 1
    fi
else
    echo "Using specified version: v$TEA_VERSION"
fi

# 2. Define variables for the download
# Detect system architecture
ARCH=$(uname -m)
case "$ARCH" in
    x86_64)
        ARCHITECTURE="amd64"
        ;;
    aarch64|arm64)
        ARCHITECTURE="arm64"
        ;;
    i386|i686)
        ARCHITECTURE="386"
        ;;
    armv7l|armv6l)
        ARCHITECTURE="arm"
        ;;
    *)
        echo -e "${RED}Error: Unsupported architecture: $ARCH${NC}" >&2
        exit 1
        ;;
esac

# Construct download URLs
DOWNLOAD_URL="https://gitea.com/gitea/tea/releases/download/v${TEA_VERSION}/tea-${TEA_VERSION}-linux-${ARCHITECTURE}"
CHECKSUM_URL="https://gitea.com/gitea/tea/releases/download/v${TEA_VERSION}/checksums.txt"

# Determine installation directory based on privileges
# Check if we can write to /usr/local/bin (requires root/sudo)
if [[ -w "/usr/local/bin" ]] || [[ "$EUID" -eq 0 ]]; then
    INSTALL_DIR="/usr/local/bin"
else
    INSTALL_DIR="$HOME/.local/bin"
fi

# Define file names and temp locations
FILE_NAME="tea"
TEMP_FILE="/tmp/tea-${TEA_VERSION}"
TEMP_CHECKSUM="/tmp/tea-checksums.txt"

# 3. Check if file already exists
if [[ -f "$INSTALL_DIR/$FILE_NAME" ]] && [[ "$FORCE" != true ]]; then
    # Prompt user before overwriting existing installation
    echo -n "tea already exists in $INSTALL_DIR. Overwrite? (Y/N): "
    read -r response
    if [[ ! "$response" =~ ^[Yy]$ ]]; then
        echo "Installation cancelled."
        exit 0
    fi
fi

# 4. Create the installation directory if it doesn't exist
echo "Creating installation directory: $INSTALL_DIR"
if [[ ! -d "$INSTALL_DIR" ]]; then
    if ! mkdir -p "$INSTALL_DIR"; then
        echo -e "${RED}Error: Failed to create installation directory${NC}" >&2
        exit 1
    fi
fi

# 5. Download the binary and checksum
echo "Downloading tea CLI v$TEA_VERSION for $ARCHITECTURE..."

# Use curl if available, otherwise use wget
if command -v curl &> /dev/null; then
    if ! curl -fL "$DOWNLOAD_URL" -o "$TEMP_FILE"; then
        echo -e "${RED}Error: Failed to download the file. Please check the URL and version number.${NC}" >&2
        rm -f "$TEMP_FILE"
        exit 1
    fi
elif command -v wget &> /dev/null; then
    if ! wget -q "$DOWNLOAD_URL" -O "$TEMP_FILE"; then
        echo -e "${RED}Error: Failed to download the file. Please check the URL and version number.${NC}" >&2
        rm -f "$TEMP_FILE"
        exit 1
    fi
else
    echo -e "${RED}Error: Neither curl nor wget is available${NC}" >&2
    exit 1
fi
echo "Binary downloaded successfully."

# Try to download checksum file for verification (optional but recommended)
CHECKSUM_AVAILABLE=false
echo "Attempting to download checksum file..."
if command -v curl &> /dev/null; then
    if curl -fL "$CHECKSUM_URL" -o "$TEMP_CHECKSUM" 2>/dev/null; then
        CHECKSUM_AVAILABLE=true
        echo "Checksum file downloaded."
    fi
elif command -v wget &> /dev/null; then
    if wget -q "$CHECKSUM_URL" -O "$TEMP_CHECKSUM" 2>/dev/null; then
        CHECKSUM_AVAILABLE=true
        echo "Checksum file downloaded."
    fi
fi

if [[ "$CHECKSUM_AVAILABLE" != true ]]; then
    echo -e "${YELLOW}Warning: Checksum file not available for this version. Skipping verification.${NC}"
fi

# 6. Verify checksum (if available)
if [[ "$CHECKSUM_AVAILABLE" == true ]]; then
    echo "Verifying file integrity..."
    
    # Check if sha256sum is available
    if ! command -v sha256sum &> /dev/null; then
        echo -e "${YELLOW}Warning: sha256sum not available. Skipping checksum verification.${NC}"
    else
        # Calculate SHA256 hash of downloaded file
        DOWNLOADED_HASH=$(sha256sum "$TEMP_FILE" | awk '{print $1}')
        
        # Parse checksums.txt to find the hash for our specific file
        # The checksums file format is: "hash  filename" (two spaces)
        EXPECTED_FILE_NAME="tea-${TEA_VERSION}-linux-${ARCHITECTURE}"
        EXPECTED_HASH=$(grep -E "^[a-fA-F0-9]+\s+${EXPECTED_FILE_NAME}$" "$TEMP_CHECKSUM" | awk '{print $1}')
        
        if [[ -z "$EXPECTED_HASH" ]]; then
            echo -e "${YELLOW}Warning: Could not find checksum for $EXPECTED_FILE_NAME in checksums.txt${NC}"
            echo -n "Continue without checksum verification? (Y/N): "
            read -r response
            if [[ ! "$response" =~ ^[Yy]$ ]]; then
                rm -f "$TEMP_FILE" "$TEMP_CHECKSUM"
                exit 1
            fi
        elif [[ "$DOWNLOADED_HASH" == "$EXPECTED_HASH" ]]; then
            echo -e "${GREEN}Checksum verification passed.${NC}"
        else
            echo -e "${RED}Error: Checksum verification failed! Downloaded file may be corrupted or tampered with.${NC}" >&2
            echo "Expected: $EXPECTED_HASH"
            echo "Got: $DOWNLOADED_HASH"
            rm -f "$TEMP_FILE" "$TEMP_CHECKSUM"
            exit 1
        fi
    fi
fi

# 7. Move file to installation directory and make it executable
if ! mv "$TEMP_FILE" "$INSTALL_DIR/$FILE_NAME"; then
    echo -e "${RED}Error: Failed to move file to installation directory${NC}" >&2
    rm -f "$TEMP_FILE" "$TEMP_CHECKSUM"
    exit 1
fi

if ! chmod +x "$INSTALL_DIR/$FILE_NAME"; then
    echo -e "${RED}Error: Failed to make file executable${NC}" >&2
    rm -f "$INSTALL_DIR/$FILE_NAME" "$TEMP_CHECKSUM"
    exit 1
fi

echo "Installed to $INSTALL_DIR/$FILE_NAME"
rm -f "$TEMP_CHECKSUM"

# 8. Add the directory to PATH if necessary
echo ""
echo "Updating PATH environment variable..."

# Check if the directory is already in PATH
if [[ ":$PATH:" == *":$INSTALL_DIR:"* ]]; then
    echo "Directory is already in PATH."
else
    echo -e "${YELLOW}Directory is not in PATH.${NC}"
    
    # Determine which shell configuration file to update
    if [[ -n "$ZSH_VERSION" ]]; then
        SHELL_CONFIG="$HOME/.zshrc"
    elif [[ -n "$BASH_VERSION" ]]; then
        if [[ -f "$HOME/.bashrc" ]]; then
            SHELL_CONFIG="$HOME/.bashrc"
        elif [[ -f "$HOME/.bash_profile" ]]; then
            SHELL_CONFIG="$HOME/.bash_profile"
        fi
    fi
    
    if [[ -n "$SHELL_CONFIG" ]]; then
        # Check if PATH export already exists in config file
        if ! grep -q "export PATH=\"\$PATH:$INSTALL_DIR\"" "$SHELL_CONFIG" 2>/dev/null; then
            echo "" >> "$SHELL_CONFIG"
            echo "# Added by tea installer" >> "$SHELL_CONFIG"
            echo "export PATH=\"\$PATH:$INSTALL_DIR\"" >> "$SHELL_CONFIG"
            echo -e "${GREEN}Added to PATH in $SHELL_CONFIG${NC}"
            echo "You may need to restart your terminal or run: source $SHELL_CONFIG"
        else
            echo "PATH entry already exists in $SHELL_CONFIG"
        fi
    else
        echo -e "${YELLOW}Warning: Could not determine shell configuration file.${NC}"
        echo "You may need to add '$INSTALL_DIR' to your PATH manually."
    fi
fi

# 9. Verification
echo ""
echo "Verification:"
if command -v tea &> /dev/null; then
    VERSION_OUTPUT=$(tea --version 2>&1)
    echo -e "${GREEN}$VERSION_OUTPUT${NC}"
elif [[ -x "$INSTALL_DIR/$FILE_NAME" ]]; then
    VERSION_OUTPUT=$("$INSTALL_DIR/$FILE_NAME" --version 2>&1)
    echo -e "${GREEN}$VERSION_OUTPUT${NC}"
else
    echo -e "${YELLOW}Warning: Could not execute tea. PATH may not be updated in this session.${NC}"
fi

echo ""
echo -e "${CYAN}Installation complete! Run 'tea login add' to start configuring your Gitea instance.${NC}"
if [[ ":$PATH:" != *":$INSTALL_DIR:"* ]]; then
    echo -e "${YELLOW}Note: If 'tea' command is not found, restart your terminal or reload PATH with:${NC}"
    if [[ -n "$SHELL_CONFIG" ]]; then
        echo -e "${GRAY}  source $SHELL_CONFIG${NC}"
    else
        echo -e "${GRAY}  export PATH=\"\$PATH:$INSTALL_DIR\"${NC}"
    fi
fi