import os

const vexe = os.real_path(os.getenv_opt('VEXE') or { @VEXE })
const symlink_usage = 'usage: v symlink [directory]'

struct SymlinkOptions {
    link_dir  string
    github_ci bool
}

fn main() {
    at_exit(|| os.rmdir_all(os.vtmp_dir()) or {}) or {}
    options := parse_symlink_options(os.args[1..]) or {
        println(symlink_usage)
        exit(1)
    }
    if options.github_ci {
        setup_symlink_github()
        return
    }
    setup_symlink(options.link_dir)
}

fn parse_symlink_options(raw_args []string) !SymlinkOptions {
    args := trim_symlink_command(raw_args)
    if args.len == 0 {
        return SymlinkOptions{}
    }
    if args == ['-githubci'] {
        // TODO: [AFTER 2024-09-31] remove `-githubci` flag and function and only print usage and exit(1) .
        if os.getenv('GITHUB_JOB') != '' {
            println('::warning::Use `v symlink` instead of `v symlink -githubci`')
        }
        return SymlinkOptions{
            github_ci: true
        }
    }
    if args.len == 1 {
        return SymlinkOptions{
            link_dir: args[0]
        }
    }
    return error(symlink_usage)
}

fn trim_symlink_command(raw_args []string) []string {
    if raw_args.len > 0 && raw_args[0] == 'symlink' {
        return raw_args[1..]
    }
    return raw_args
}

fn normalized_link_dir(custom_link_dir string) string {
    if custom_link_dir != '' {
        return os.expand_tilde_to_home(custom_link_dir)
    }
    return default_link_dir()
}

fn setup_symlink_github() {
    // We append V's install location (which should
    // be the current directory) to the PATH environment variable.

    // Resources:
    // 1. https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#environment-files
    // 2. https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#setting-an-environment-variable
    mut content := os.read_file(os.getenv('GITHUB_PATH')) or {
        eprintln('The `GITHUB_PATH` env variable is not defined.')
        eprintln('    This command: `v symlink -githubci` is intended to be used within GithubActions .yml files.')
        eprintln('    It also needs to be run *as is*, *** without `sudo` ***, otherwise it will not work.')
        eprintln('    For local usage, outside CIs, on !windows, prefer `sudo ./v symlink` .')
        eprintln('    On windows, use `.\\v.exe symlink` instead.')
        exit(1)
    }
    content += '\n${os.getwd()}\n'
    os.write_file(os.getenv('GITHUB_PATH'), content) or { panic('Failed to write to GITHUB_PATH.') }
}