IT_HASH: &str = env!("VERSION_AND_GIT_HASH");

static CWD: RwLock<Option<PathBuf>> = RwLock::new(None);

static RUNTIME_DIRS: once_cell::sync::Lazy<Vec<PathBuf>> =
    once_cell::sync::Lazy::new(prioritize_runtime_dirs);

static CONFIG_FILE: once_cell::sync::OnceCell<PathBuf> = once_cell::sync::OnceCell::new();

static LOG_FILE: once_cell::sync::OnceCell<PathBuf> = once_cell::sync::OnceCell::new();

// Get the current working directory.
// This information is managed internally as the call to std::env::current_dir
// might fail if the cwd has been deleted.
pub fn current_working_dir() -> PathBuf {
    if let Some(path) = &*CWD.read().unwrap() {
        return path.clone();
    }

    let path = std::env::current_dir()
        .and_then(dunce::canonicalize)
        .expect("Couldn't determine current working directory");
    let mut cwd = CWD.write().unwrap();
    *cwd = Some(path.clone());

    path
}

pub fn set_current_working_dir(path: PathBuf) -> std::io::Result<()> {
    let path = dunce::canonicalize(path)?;
    std::env::set_current_dir(path.clone())?;
    let mut cwd = CWD.write().unwrap();
    *cwd = Some(path);
    Ok(())
}

pub fn initialize_config_file(specified_file: Option<PathBuf>) {
    let config_file = specified_file.unwrap_or_else(default_config_file);
    ensure_parent_dir(&config_file);
    CONFIG_FILE.set(config_file).ok();
}

pub fn initialize_log_file(specified_file: Option<PathBuf>) {
    let log_file = specified_file.unwrap_or_else(default_log_file);
    ensure_parent_dir(&log_file);
    LOG_FILE.set(log_file).ok();
}

/// A list of runtime directories from highest to lowest priority
///
/// The priority is:
///
/// 1. sibling directory to `CARGO_MANIFEST_DIR` (if environment variable is set)
/// 2. subdirectory of user config directory (always included)
/// 3. `HELIX_RUNTIME` (if environment variable is set)
/// 4. subdirectory of path to helix executable (always included)
///
/// Postcondition: returns at least two paths (they might not exist).
fn prioritize_runtime_dirs() -> Vec<PathBuf> {
    const RT_DIR: &str = "runtime";
    // Adding higher priority first
    let mut rt_dirs = Vec::new();
    if let Ok(dir) = std::env::var("CARGO_MANIFEST_DIR") {
        // this is the directory of the crate being run by cargo, we need the workspace path so we take the parent
        let path = PathBuf::from(dir).parent().unwrap().join(RT_DIR);
        log::debug!("runtime dir: {}", path.to_string_lossy());
        rt_dirs.push(path);
    }

    let conf_rt_dir = config_dir().join(RT_DIR);
    rt_dirs.push(conf_rt_dir);

    if let Ok(dir) = std::env::var("HELIX_RUNTIME") {
        rt_dirs.push(dir.into());
    }

    // fallback to location of the executable being run
    // canonicalize the path in case the executable is symlinked
    let exe_rt_dir = std::env::current_exe()
        .ok()
        .and_then(|path| std::fs::canonicalize(path).ok())
        .and_then(|path| path.parent().map(|path| path.to_path_buf().join(RT_DIR)))
        .unwrap();
    rt_dirs.push(exe_rt_dir);
    rt_dirs
}

/// Runtime directories ordered from highest to lowest priority
///
/// All directories should be checked when looking for files.
///
/// Postcondition: returns at least one path (it might not exist).
pub fn runtime_dirs() -> &'static [PathBuf] {
    &RUNTIME_DIRS
}

/// Find file with path relative to runtime directory
///
/// `rel_path` should be the relative path from within the `runtime/` directory.
/// The valid runtime directories are searched in priority order and the first
/// file found to exist is returned, otherwise None.
fn find_runtime_file(rel_path: &Path) -> Option<PathBuf> {
    RUNTIME_DIRS.iter().find_map(|rt_dir| {
        let path = rt_dir.join(rel_path);
        if path.exists() {
            Some(path)
        } else {
            None
        }
    })
}

/// Find file with path relative to runtime directory
///
/// `rel_path` should be the relative path from within the `runtime/` directory.
/// The valid runtime directories are searched in priority order and the first
/// file found to exist is returned, otherwise the path to the final attempt
/// that failed.
pub fn runtime_file(rel_path: &Path) -> PathBuf {
    find_runtime_file(rel_path).unwrap_or_else(|| {
        RUNTIME_DIRS
            .last()
            .map(|dir| dir.join(rel_path))
            .unwrap_or_default()
    })
}

pub fn config_dir() -> PathBuf {
    // TODO: allow env var override
    let strategy = choose_base_strategy().expect("Unable to find the config directory!");
    let mut path = strategy.config_dir();
    path.push("helix");
    path
}

pub fn cache_dir() -> PathBuf {
    // TODO: allow env var override
    let strategy = choose_base_strategy().expect("Unable to find the config directory!");
    let mut path = strategy.cache_dir();
    path.push("helix");
    path
}

pub fn config_file() -> PathBuf {
    CONFIG_FILE.get().map(|path| path.to_path_buf()).unwrap()
}

pub fn log_file() -> PathBuf {
    LOG_FILE.get().map(|path| path.to_path_buf()).unwrap()
}

pub fn workspace_config_file() -> PathBuf {
    find_workspace().0.join(".helix").join("config.toml")
}

pub fn lang_config_file() -> PathBuf {
    config_dir().join("languages.toml")
}

pub fn default_log_file() -> PathBuf {
    cache_dir().join("helix.log")
}

/// Merge two TOML documents, merging values from `right` onto `left`
///
/// When an array exists in both `left` and `right`, `right`'s array is
/// used. When a table exists in both `left` and `right`, the merged table
/// consists of all keys in `left`'s table unioned with all keys in `right`
/// with the values of `right` being merged recursively onto values of
/// `left`.
///
/// `merge_toplevel_arrays` controls whether a top-level array in the TOML
/// document is merged instead of overridden. This is useful for TOML
/// documents that use a top-level array of values like the `languages.toml`,
/// where one usually wants to override or add to the array instead of
/// replacing it altogether.
pub fn merge_toml_values(left: toml::Value, right: toml::Value, merge_depth: usize) -> toml::Value {
    use toml::Value;

    fn get_name(v: &Value) -> Option<&str> {
        v.get("name").and_then(Value::as_str)
    }

    match (left, right) {
        (Value::Array(mut left_items), Value::Array(right_items)) => {
            // The top-level arrays should be merged but nested arrays should
            // act as overrides. For the `languages.toml` config, this means
            // that you can specify a sub-set of languages in an overriding
            // `languages.toml` but that nested arrays like Language Server
            // arguments are replaced instead of merged.
            if merge_depth > 0 {
                left_items.reserve(right_items.len());
                for rvalue in right_items {
                    let lvalue = get_name(&rvalue)
                        .and_then(|rname| {
                            left_items.iter().position(|v| get_name(v) == Some(rname))
                        })
                        .map(|lpos| left_items.remove(lpos));
                    let mvalue = match lvalue {
                        Some(lvalue) => merge_toml_values(lvalue, rvalue, merge_depth - 1),
                        None => rvalue,
                    };
                    left_items.push(mvalue);
                }
                Value::Array(left_items)
            } else {
                Value::Array(right_items)
            }
        }
        (Value::Table(mut left_map), Value::Table(right_map)) => {
            if merge_depth > 0 {
                for (rname, rvalue) in right_map {
                    match left_map.remove(&rname) {
                        Some(lvalue) => {
                            let merged_value = merge_toml_values(lvalue, rvalue, merge_depth - 1);
                            left_map.insert(rname, merged_value);
                        }
                        None => {
                            left_map.insert(rname, rvalue);
                        }
                    }
                }
                Value::Table(left_map)
            } else {
                Value::Table(right_map)
            }
        }
        // Catch everything else we didn't handle, and use the right value
        (_, value) => value,
    }
}

/// Finds the current workspace folder.
/// Used as a ceiling dir for LSP root resolution, the filepicker and potentially as a future filewatching root
///
/// This function starts searching the FS upward from the CWD
/// and returns the first directory that contains either `.git` or `.helix`.
/// If no workspace was found returns (CWD, true).
/// Otherwise (workspace, false) is returned
pub fn find_workspace() -> (PathBuf, bool) {
    let current_dir = current_working_dir();
    for ancestor in current_dir.ancestors() {
        if ancestor.join(".git").exists() || ancestor.join(".helix").exists() {
            return (ancestor.to_owned(), false);
        }
    }

    (current_dir, true)
}

fn default_config_file() -> PathBuf {
    config_dir().join("config.toml")
}

fn ensure_parent_dir(path: &Path) {
    if let Some(parent) = path.parent() {
        if !parent.exists() {
            std::fs::create_dir_all(parent).ok();
        }
    }
}

#[cfg(test)]
mod merge_toml_tests {
    use std::str;

    use super::{current_working_dir, merge_toml_values, set_current_working_dir};
    use toml::Value;

    #[test]
    fn current_dir_is_set() {
        let new_path = dunce::canonicalize(std::env::temp_dir()).unwrap();
        let cwd = current_working_dir();
        assert_ne!(cwd, new_path);

        set_current_working_dir(new_path.clone()).expect("Couldn't set new path");

        let cwd = current_working_dir();
        assert_eq!(cwd, new_path);
    }

    #[test]
    fn language_toml_map_merges() {
        const USER: &str = r#"
        [[language]]
        name = "nix"
        test = "bbb"
        indent = { tab-width = 4, unit = "    ", test = "aaa" }
        "#;

        let base = include_bytes!("../../languages.toml");
        let base = str::from_utf8(base).expect("Couldn't parse built-in languages config");
        let base: Value = toml::from_str(base).expect("Couldn't parse built-in languages config");
        let user: Value = toml::from_str(USER).unwrap();

        let merged = merge_toml_values(base, user, 3);
        let languages = merged.get("language").unwrap().as_array().unwrap();
        let nix = languages
            .iter()
            .find(|v| v.get("name").unwrap().as_str().unwrap() == "nix")
            .unwrap();
        let nix_indent = nix.get("indent").unwrap();

        // We changed tab-width and unit in indent so check them if they are the new values
        assert_eq!(
            nix_indent.get("tab-width").unwrap().as_integer().unwrap(),
            4
        );
        assert_eq!(nix_indent.get("unit").unwrap().as_str().unwrap(), "    ");
        // We added a new keys, so check them
        assert_eq!(nix.get("test").unwrap().as_str().unwrap(), "bbb");
        assert_eq!(nix_indent.get("test").unwrap().as_str().unwrap(), "aaa");
        // We didn't change comment-token so it should be same
        assert_eq!(nix.get("comment-token").unwrap().as_str().unwrap(), "#");
    }

    #[test]
    fn language_toml_nested_array_merges() {
        const USER: &str = r#"
        [[language]]
        name = "typescript"
        language-server = { command = "deno", args = ["lsp"] }
        "#;

        let base = include_bytes!("../../languages.toml");
        let base = str::from_utf8(base).expect("Couldn't parse built-in languages config");
        let base: Value = toml::from_str(base).expect("Couldn't parse built-in languages config");
        let user: Value = toml::from_str(USER).unwrap();

        let merged = merge_toml_values(base, user, 3);
        let languages = merged.get("language").unwrap().as_array().unwrap();
        let ts = languages
            .iter()
            .find(|v| v.get("name").unwrap().as_str().unwrap() == "typescript")
            .unwrap();
        assert_eq!(
            ts.get("language-server")
                .unwrap()
                .get("args")
                .unwrap()
                .as_array()
                .unwrap(),
            &vec![Value::String("lsp".into())]
        )
    }
}