# Git Credential Manager Installer

A comprehensive installer script for Git Credential Manager (GCM) that supports multiple Linux distributions and installation methods.

## Features

- **Version Checking**: Only downloads and installs if newer version is available
- **Multiple Installation Methods**:
  - Package manager (apt, yum, dnf, pacman, zypper)
  - DEB packages (Debian/Ubuntu)
  - Tar.gz archives (universal)
- **Cross-Platform Support**: Debian, Ubuntu, RHEL, CentOS, Fedora, Arch, openSUSE
- **Architecture Support**: x86_64 (amd64), ARM64 (arm64), ARM (armv7l)
- **Automatic Updates**: Fetches latest version from GitHub releases
- **Force Reinstall**: Option to force reinstallation even if up-to-date

## Usage

### Basic Usage
```bash
# Install latest version (only if newer than current)
./install-git-credential-manager.sh

# Install specific version
./install-git-credential-manager.sh -v v2.6.0

# Force reinstall even if up-to-date
./install-git-credential-manager.sh --force
```

### Installation Methods
```bash
# Force installation from package manager
./install-git-credential-manager.sh --package

# Force installation from DEB package
./install-git-credential-manager.sh --deb

# Force installation from tarball
./install-git-credential-manager.sh --tarball
```

### Check Configuration Only
```bash
# Check current Git credential configuration without installing
./install-git-credential-manager.sh --checks

# Example output:
# ✓ Global credential helper: manager
# ✓ GitHub credential helper configured
# ✗ GitLab credential helper not configured
# ✗ Azure DevOps useHttpPath not configured
# ✗ Bitbucket credential helper not configured
# ✓ Gitea credential helpers configured (1 found)
#
# Run these commands to complete the configuration:
#   git config --global credential.https://gitlab.com.helper manager
#   git config --global credential.https://dev.azure.com.useHttpPath true
#   git config --global credential.https://bitbucket.org.helper manager
```

### Help
```bash
./install-git-credential-manager.sh --help
```

## Installation Logic

### Version Checking
1. **Check Current Version**: Detects installed GCM version
2. **Fetch Latest**: Gets latest version from GitHub API
3. **Compare Versions**: Only proceeds if newer version available
4. **Force Override**: `--force` flag bypasses version check

### Installation Priority
1. **Package Manager** (preferred):
   - Debian/Ubuntu: `apt install git-credential-manager`
   - Arch Linux: `pacman -S git-credential-manager`
   - Others: Falls back to manual installation

2. **Distribution-Specific**:
   - Debian/Ubuntu: Downloads `.deb` package
   - Other Linux: Downloads `.tar.gz` archive

3. **Universal Fallback**:
   - Downloads tarball for any architecture
   - Extracts and installs binary to `/usr/local/bin`

## System Requirements

### Required
- `curl` or `wget` (for downloading)
- `sudo` access (for system-wide installation)
- Git (for configuration)

### Optional
- Package manager access (for package installations)
- Internet connection (for downloading releases)

## File Locations

### Installation Directory
- Binary: `/usr/local/bin/git-credential-manager`
- Symlink: `/usr/local/bin/git-credential-manager-core`
- Libraries: `/usr/local/bin/lib*.so`

### Configuration
- Git config: `~/.gitconfig`
- Credential storage: Platform-specific secure storage

## Version Comparison

The installer uses semantic version comparison:
- **Format**: `vX.Y.Z` (e.g., `v2.6.1`)
- **Logic**: Compares major, minor, patch versions
- **Build Info**: Ignores build hashes/identifiers

### Examples
```bash
# Current: v2.6.1, Latest: v2.6.1 → No update needed
# Current: v2.6.0, Latest: v2.6.1 → Update needed
# Current: v2.6.1, Latest: v2.6.0 → No update needed (newer installed)
```

## Integration with Setup Script

The installer is automatically integrated with the main Git repository setup script:

1. **Detection**: Checks for existing credential managers
2. **Offer Installation**: Prompts to install GCM if none found
3. **Configuration**: Sets up Git to use the credential manager
4. **Domain-Specific**: Configures for specific Gitea instances

## Security Features

- **Official Releases**: Downloads from official GitHub releases
- **Checksum Verification**: Can verify package integrity (future enhancement)
- **Secure Storage**: Uses OS keyring for credential storage
- **No Plain Text**: Never stores credentials in plain text

## Troubleshooting

### Version Detection Issues
```bash
# Check current version manually
git-credential-manager --version

# Force reinstall if version detection fails
./install-git-credential-manager.sh --force
```

### Permission Issues
```bash
# Ensure proper permissions
sudo chown root:root /usr/local/bin/git-credential-manager
sudo chmod 755 /usr/local/bin/git-credential-manager
```

### Network Issues
```bash
# Use specific version if network blocks GitHub API
./install-git-credential-manager.sh -v v2.6.1
```

## Examples

### Typical Workflow
```bash
# Check if update needed
./install-git-credential-manager.sh

# Output if up-to-date:
# [SUCCESS] You already have the latest version (v2.6.1)
# [SUCCESS] No installation needed. Exiting.

# Output if update available:
# [INFO] Current version: v2.6.0
# [INFO] Latest version: v2.6.1
# [INFO] Newer version available: v2.6.1 > v2.6.0
# [SUCCESS] Installation completed successfully!
```

### Automated Installation
```bash
# Script for automated setup
#!/bin/bash
./install-git-credential-manager.sh --force --package
git config --global credential.helper manager
```

## Post-Installation Configuration Check

After successful installation, the installer automatically checks and configures all required Git presets:

### ✅ Preset Verification
The installer checks these configurations:
- **Global credential helper**: `credential.helper manager`
- **GitHub**: `credential.https://github.com.helper manager`
- **GitLab**: `credential.https://gitlab.com.helper manager`
- **Bitbucket**: `credential.https://bitbucket.org.helper manager`
- **Azure DevOps**: `credential.https://dev.azure.com.useHttpPath true`
- **Gitea servers**: Domain-specific credential helpers

### 📋 Configuration Report
The installer provides:
- **Status summary**: Shows which presets are configured (✓) or missing (✗)
- **Exact commands**: Lists the exact `git config` commands needed
- **Testing guidance**: Commands to verify the configuration
- **Service-specific advice**: Tailored guidance for different Git hosting services

### 🔧 Manual Configuration
If presets are missing, the installer shows exactly what to run:

```bash
# Example output for missing presets:
Run these commands to complete the configuration:
  git config --global credential.https://gitlab.com.helper manager
  git config --global credential.https://dev.azure.com.useHttpPath true
  git config --global credential.https://bitbucket.org.helper manager
  # For Gitea servers, configure domain-specific helper:
  git config --global credential.https://go-gitea.mywire.org.helper manager

After configuring, test with:
  git config --global --list | grep credential
```

## Integration with Setup Script

The installer integrates seamlessly with the main setup script:
- Automatically called when Git Credential Manager is needed
- Respects user preferences for installation location
- Provides clear feedback on installation strategy
- Handles both new installations and updates
- **Performs comprehensive preset checking and configuration**

## Contributing

To add support for new distributions or architectures:

1. Update `detect_os()` function for new package managers
2. Add architecture detection in `get_arch()` function
3. Update installation methods in `install_from_*()` functions
4. Test with target distribution

## License

This installer script follows the same license as Git Credential Manager (MIT).