module main

import os
import v.help
import v.vmod

struct LinkedProject {
    name        string
    project_dir string
    link_path   string
}

fn vpm_link(query []string) {
    if settings.is_help {
        help.print_and_exit('link')
    }
    ensure_no_query_for_project_command('link', query)
    ensure_vmodules_dir_exist()

    project := get_project_for_linking() or {
        vpm_error(err.msg())
        exit(1)
    }
    if project.project_dir == os.real_path(project.link_path) {
        println('Module `${project.name}` is already available in `${fmt_mod_path(project.link_path)}`.')
        return
    }
    if os.exists(project.link_path) || os.is_link(project.link_path) {
        if os.is_link(project.link_path) {
            if os.real_path(project.link_path) == project.project_dir {
                println('Module `${project.name}` is already linked in `${fmt_mod_path(project.link_path)}`.')
                return
            }
            vpm_error('`${project.name}` is already linked at `${fmt_mod_path(project.link_path)}`.',
                details: 'Run `v unlink` first to replace it.'
            )
            exit(1)
        }
        vpm_error('`${project.name}` already exists at `${fmt_mod_path(project.link_path)}`.')
        exit(1)
    }
    parent_dir := os.dir(project.link_path)
    os.mkdir_all(parent_dir) or {
        vpm_error('failed to create `${fmt_mod_path(parent_dir)}`.', details: err.msg())
        exit(1)
    }
    os.symlink(project.project_dir, project.link_path) or {
        vpm_error('failed to link `${project.name}`.', details: err.msg())
        exit(1)
    }
    println('Linked `${project.name}` to `${fmt_mod_path(project.link_path)}`.')
}

fn vpm_unlink(query []string) {
    if settings.is_help {
        help.print_and_exit('unlink')
    }
    ensure_no_query_for_project_command('unlink', query)

    project := get_project_for_linking() or {
        vpm_error(err.msg())
        exit(1)
    }
    if !os.exists(project.link_path) && !os.is_link(project.link_path) {
        println('Module `${project.name}` is not linked in `${fmt_mod_path(project.link_path)}`.')
        return
    }
    if !os.is_link(project.link_path) {
        vpm_error('`${project.name}` at `${fmt_mod_path(project.link_path)}` is not a symlink.')
        exit(1)
    }
    remove_symlink(project.link_path) or {
        vpm_error('failed to unlink `${project.name}`.', details: err.msg())
        exit(1)
    }
    cleanup_empty_link_parent_dirs(project.link_path)
    println('Unlinked `${project.name}` from `${fmt_mod_path(project.link_path)}`.')
}

fn ensure_no_query_for_project_command(command string, query []string) {
    if query.len == 0 {
        return
    }
    vpm_error('`${command}` does not accept package names.',
        details: 'Run `v ${command}` from inside the project directory.'
    )
    exit(2)
}

fn get_project_for_linking() !LinkedProject {
    wrkdir := os.getwd()
    mut mcache := vmod.get_cache()
    vmod_location := mcache.get_by_folder(wrkdir)
    if vmod_location.vmod_file == '' {
        return error('no `v.mod` file found in `${wrkdir}` or its parent directories.')
    }
    manifest := vmod.from_file(vmod_location.vmod_file)!
    if manifest.name.trim_space() == '' {
        return error('`${vmod_location.vmod_file}` is missing the `name` field.')
    }
    mod_path := normalize_mod_path(manifest.name.replace('.', os.path_separator))
    vmodules_path := if os.is_dir(settings.vmodules_path) {
        os.real_path(settings.vmodules_path)
    } else {
        settings.vmodules_path
    }
    return LinkedProject{
        name:        manifest.name
        project_dir: os.real_path(vmod_location.vmod_folder)
        link_path:   os.join_path(vmodules_path, mod_path)
    }
}

fn remove_symlink(path string) ! {
    os.rm(path) or {
        $if windows {
            os.rmdir(path)!
        } $else {
            return err
        }
    }
}

fn cleanup_empty_link_parent_dirs(link_path string) {
    vmodules_path := if os.is_dir(settings.vmodules_path) {
        os.real_path(settings.vmodules_path)
    } else {
        settings.vmodules_path
    }
    mut parent := os.dir(link_path)
    for parent != vmodules_path && parent != os.dir(parent) {
        if !os.is_dir(parent) || !os.is_dir_empty(parent) {
            break
        }
        os.rmdir(parent) or { break }
        parent = os.dir(parent)
    }
}