//! path_serializer is used in cases where we need to serialize relative Path
//! and PathBuf objects in a way that's cross-platform.
//!
//! This is used for the snapshot testing system to make sure that snapshots
//! that reference local paths that are generated on Windows don't fail when run
//! in systems that use a different directory separator.
//!
//! To use, annotate your PathBuf or Option<PathBuf> field with the correct
//! serializer function:
//!
//! ```
//! # use std::path::PathBuf;
//! # use serde_derive::{Serialize, Deserialize};
//!
//! #[derive(Serialize, Deserialize)]
//! struct Mine {
//!     name: String,
//!
//!     // Use 'crate' instead of librojo if writing code inside Rojo
//!     #[serde(serialize_with = "librojo::path_serializer::serialize")]
//!     source_path: PathBuf,
//!
//!     #[serde(serialize_with = "librojo::path_serializer::serialize_option")]
//!     maybe_path: Option<PathBuf>,
//! }
//! ```
//!
//! **The methods in this module can only handle relative paths, since absolute
//! paths are never portable.**

use std::path::{Component, Path};

use serde::Serializer;

pub fn serialize_option<S, T>(maybe_path: &Option<T>, serializer: S) -> Result<S::Ok, S::Error>
    where S: Serializer,
          T: AsRef<Path>,
{
    match maybe_path {
        Some(path) => serialize(path, serializer),
        None => serializer.serialize_none()
    }
}

pub fn serialize<S, T>(path: T, serializer: S) -> Result<S::Ok, S::Error>
    where S: Serializer,
          T: AsRef<Path>,
{
    let path = path.as_ref();

    assert!(path.is_relative(), "path_serializer can only handle relative paths");

    let mut output = String::new();

    for component in path.components() {
        if !output.is_empty() {
            output.push('/');
        }

        match component {
            Component::CurDir => output.push('.'),
            Component::ParentDir => output.push_str(".."),
            Component::Normal(piece) => output.push_str(piece.to_str().unwrap()),
            _ => panic!("path_serializer cannot handle absolute path components"),
        }
    }

    serializer.serialize_str(&output)
}