// Copyright: Ankitects Pty Ltd and contributors
// License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html

//! Env vars that control behaviour:
//! - FTL_SRC can be pointed at /ftl/BUILD.bazel to tell the script where the translatinos
//! in the source tree can be found. If not set (when building from cargo), the script
//! will look in the parent folders instead.
//! - RSLIB_FTL_ROOT should be set to the l10n.toml file inside the core translation repo.
//! - EXTRA_FTL_ROOT should normally be set to the l10n.toml file inside the qt translation
//! repo. If it is pointed at a different location, the Qt translations will be excluded
//! and the provided translations embedded instead.

use std::path::Path;
use std::{collections::HashMap, env};
use std::{fs, path::PathBuf};

pub type TranslationsByFile = HashMap<String, String>;
pub type TranslationsByLang = HashMap<String, TranslationsByFile>;

/// Read the contents of the FTL files into a TranslationMap structure.
pub fn get_ftl_data() -> TranslationsByLang {
    let mut map = TranslationsByLang::default();

    // English templates first
    let ftl_base = source_tree_root();
    add_folder(&mut map, &ftl_base.join("core"), "templates");

    // Core translations provided?
    if let Some(path) = core_ftl_root() {
        add_translation_root(&mut map, &path, true);
    }

    // Extra templates/translations provided?
    if let Some(path) = extra_ftl_root() {
        let add_qt_templates = extra_ftl_is_desktop(&path);
        if add_qt_templates {
            add_folder(&mut map, &ftl_base.join("qt"), "templates");
        }
        add_translation_root(&mut map, &path, add_qt_templates);
    }

    map
}

/// For each .ftl file in the provided folder, add it to the translation map.
fn add_folder(map: &mut TranslationsByLang, folder: &Path, lang: &str) {
    let map_entry = map.entry(lang.to_string()).or_default();
    for entry in fs::read_dir(&folder).unwrap() {
        let entry = entry.unwrap();
        let fname = entry.file_name().to_string_lossy().to_string();
        if !fname.ends_with(".ftl") {
            continue;
        }
        let module = fname.trim_end_matches(".ftl").replace("-", "_");
        let text = fs::read_to_string(&entry.path()).unwrap();
        assert!(
            text.ends_with('\n'),
            "file was missing final newline: {:?}",
            entry
        );
        map_entry.entry(module).or_default().push_str(&text);
        // when building under Bazel changes to the .ftl files will automatically
        // be picked up, but when building under Cargo we need to declare the files
        // that should trigger a rebuild
        println!("cargo:rerun-if-changed={}", entry.path().to_str().unwrap());
    }
}

/// For each language folder in `root`, add the ftl files stored inside.
/// If ignore_templates is true, the templates/ folder will be ignored, on the
/// assumption the templates were extracted from the source tree.
fn add_translation_root(map: &mut TranslationsByLang, root: &Path, ignore_templates: bool) {
    for entry in fs::read_dir(root).unwrap() {
        let entry = entry.unwrap();
        let lang = entry.file_name().to_string_lossy().to_string();
        if ignore_templates && lang == "templates" {
            continue;
        }
        add_folder(map, &entry.path(), &lang);
    }
}

/// True if @extra_ftl points to the standard Qt translations,
/// which have a desktop/ folder.
fn extra_ftl_is_desktop(extra_ftl_root: &Path) -> bool {
    extra_ftl_root
        .file_name()
        .map(|fname| fname == "desktop")
        .unwrap_or_default()
}

fn source_tree_root() -> PathBuf {
    if let Ok(srcfile) = env::var("FTL_SRC") {
        let mut path = PathBuf::from(srcfile);
        path.pop();
        path
    } else {
        PathBuf::from("../../ftl")
    }
}

fn core_ftl_root() -> Option<PathBuf> {
    std::env::var("RSLIB_FTL_ROOT")
        .ok()
        .map(first_folder_next_to_l10n_file)
}

fn extra_ftl_root() -> Option<PathBuf> {
    std::env::var("EXTRA_FTL_ROOT")
        .ok()
        .map(first_folder_next_to_l10n_file)
}

fn first_folder_next_to_l10n_file(l10n_path: String) -> PathBuf {
    // drop the filename
    let mut path = PathBuf::from(&l10n_path);
    path.pop();
    // iterate over the folder
    for entry in path.read_dir().unwrap() {
        let entry = entry.unwrap();
        if entry.metadata().unwrap().is_dir() {
            // return the first folder we find
            return entry.path();
        }
    }
    panic!("no folder found in {}", l10n_path);
}