specta-elm 0.0.1

use std::{
    collections::{HashMap, HashSet},
    fmt::{self, Debug},
    fs::File,
    io::BufReader,
    path::{Path, PathBuf},
};

use serde_json::Value;
use specta::{
    Types,
    datatype::{DataType, Fields, NamedDataType},
};

use crate::{
    Error,
    export::{Exporter, IntoExporter},
};

// Constants {{{
pub(crate) const COMMENT_SYMBOL: &'static str = "-- ";
pub(crate) const EXTENSION: &'static str = "elm";
pub(crate) const ELM_ENUM_SYMBOL: &'static str = "type ";
pub(crate) const ELM_STRUCT_SYMBOL: &'static str = "type alias ";
pub(crate) const PRELUDE: &'static str = "generated by specta-elm";
pub(crate) const RESERVED_TYPE_NAMES: &[&str] = &[
    "if", "then", "else", "case", "of", "let", "in", "type", "module", "where", "import",
    "exposing", "as", "port",
];
// }}}
// Types {{{
fn recurse_fields(fields: &Fields) {
    match fields {
        specta::datatype::Fields::Unit => (),
        specta::datatype::Fields::Unnamed(unnamed_fields) => {
            for field in unnamed_fields.fields.iter() {
                if let Some(dt) = &field.ty {
                    recurse_dt_and_panic(&dt);
                }
            }
        }
        specta::datatype::Fields::Named(named_fields) => {
            for (_, field) in named_fields.fields.iter() {
                if let Some(dt) = &field.ty {
                    recurse_dt_and_panic(&dt);
                }
            }
        }
    }
}
fn recurse_dt_and_panic(dt: &DataType) {
    match dt {
        DataType::List(list) => recurse_dt_and_panic(&list.ty),
        DataType::Map(map) => {
            recurse_dt_and_panic(map.key_ty());
            recurse_dt_and_panic(map.value_ty());
        }
        DataType::Struct(st) => recurse_fields(&st.fields),
        DataType::Enum(en) => {
            for (_, variant) in &en.variants {
                recurse_fields(&variant.fields);
            }
        }
        DataType::Tuple(tuple) => {
            for dt in &tuple.elements {
                recurse_dt_and_panic(&dt);
            }
        }
        DataType::Nullable(data_type) => recurse_dt_and_panic(&data_type),
        DataType::Intersection(data_types) => {
            for dt in data_types {
                recurse_dt_and_panic(&dt);
            }
        }
        DataType::Reference(reference) => match reference {
            specta::datatype::Reference::Named(named_reference) => {
                match &named_reference.inner {
                    specta::datatype::NamedReferenceType::Recursive(_recursive_inline_type) => {
                        panic!("recursivity")
                    }
                    specta::datatype::NamedReferenceType::Inline { dt, .. } => {
                        recurse_dt_and_panic(&dt)
                    }
                    specta::datatype::NamedReferenceType::Reference { generics, .. } => {
                        if !generics.is_empty() {
                            panic!("generics")
                        }
                    }
                };
            }
            specta::datatype::Reference::Opaque(_opaque_reference) => panic!("opaque ref"),
        },
        DataType::Generic(_generic) => panic!("generic"),
        _ => (),
    }
}
fn guard_panic_on_unsupported_types<'a>(types: &Types) {
    for ndt in types.into_unsorted_iter() {
        if ndt.name.is_empty() {
            panic!("unnamed")
        }

        if let Some(dt) = &ndt.ty {
            recurse_dt_and_panic(&dt);
        }
    }
}
//
// }}}
// Elm {{{

#[derive(Debug, Clone)]
// #[non_exhaustive]
// pub struct Elm<E: Exporter> {
pub struct Elm {
    project: Project,
    // exporter: E,
    types: Types,
}

// impl<E: Exporter> Elm<E> {
impl Elm {
    pub fn init(types: Types, path: &str) -> Self {
        guard_panic_on_unsupported_types(&types);
        let project = Project::try_from(path).expect("no elm.json in path or path chidren");
        Elm { project, types }
        // let exporter = IntoExporter::into(output, &project);

        // Elm { exporter, project }
    }

    pub fn export<E: Exporter, O: IntoExporter<Output = E>>(
        &mut self,
        output: O,
    ) -> Result<(), Error> {
        let mut exporter = output.into(&self.project);
        exporter.export(&self.types);
        self.project.cleanup_stale_files()
    }
}

#[derive(Clone, PartialEq, Eq, Hash, Debug)]
pub enum ElmCoreLibImport {
    Dict,
    Set,
}

impl fmt::Display for ElmCoreLibImport {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str(match self {
            ElmCoreLibImport::Dict => "Dict",
            ElmCoreLibImport::Set => "Set",
        })
    }
}

// }}}
// Project {{{
#[derive(Debug, Clone)]
pub struct Project {
    src_dirs: Vec<PathBuf>,
    // config: Value,
}

impl Project {
    pub fn source_directories(&self) -> &[PathBuf] {
        self.src_dirs.as_slice()
    }
    fn cleanup_stale_files(&mut self) -> Result<(), Error> {
        for dir in &self.src_dirs {
            if dir.exists() {
                return Ok(());
            }
        }

        for dir in &self.src_dirs {
            for path in collect_existing_files(dir)? {
                if !is_generated_specta_file(&path)? {
                    continue;
                }

                std::fs::remove_file(&path).or_else(|source| {
                    if source.kind() == std::io::ErrorKind::NotFound {
                        Ok(())
                    } else {
                        Err(Error::remove_file(path.clone(), source))
                    }
                })?;
            }
            remove_empty_dirs(dir, dir)?;
        }

        Ok(())
    }
}

impl TryFrom<&str> for Project {
    type Error = Error;

    fn try_from(path: &str) -> Result<Self, Self::Error> {
        let path = PathBuf::from(path);

        let start: PathBuf = if path.is_file() {
            path.parent()
                .map(Path::to_path_buf)
                .unwrap_or_else(|| PathBuf::from("."))
        } else {
            path
        };

        let elm_json_path = search_down(&start, 2).expect("couldn't find elm.json file");

        let file =
            File::open(&elm_json_path).map_err(|e| Error::read_file(elm_json_path.clone(), e))?;

        let config: Value =
            serde_json::from_reader(BufReader::new(file)).expect("couldn't deserialize elm.json");

        let src_dirs = config
            .get("source-directories")
            .and_then(Value::as_array)
            .map(|arr| {
                arr.iter()
                    .filter_map(Value::as_str)
                    .map(|rel_dir| {
                        PathBuf::from(
                            elm_json_path
                                .parent()
                                .expect("elm project is batman (somehow elm.json exists butt no parent :l)")
                                .join(rel_dir),
                        )
                    })
                    .collect()
            })
            .unwrap_or_default();

        // Ok(Project { src_dirs, config })
        Ok(Project { src_dirs })
    }
}

fn search_down(root: &Path, max_depth: usize) -> Option<PathBuf> {
    let candidate = root.join("elm.json");
    if candidate.is_file() {
        return Some(candidate);
    }
    if max_depth == 0 {
        return None;
    }
    let entries = std::fs::read_dir(root).ok()?;
    for entry in entries.filter_map(Result::ok) {
        let entry_path = entry.path();
        if entry_path.is_dir() {
            if let Some(found) = search_down(&entry_path, max_depth - 1) {
                return Some(found);
            }
        }
    }
    None
}

// }}}
// References {{{
pub type ReferenceExports = HashMap<String, NamedDataType>;

// #[derive(Default, Debug)]
// pub struct References<'a> {
//     pool: HashSet<&'a NamedReference>,
// }
//
// impl<'a> References<'a> {
//     pub fn collect(types: &'a Types) -> Self {
//         let mut refs = References::default();
//
//         for ndt in types.into_sorted_iter() {
//             if let Some(dt) = &ndt.ty {
//                 refs.collect_refs(&dt);
//                 // refs.exports.insert(ndt.name.to_string(), ndt.clone());
//             }
//         }
//
//         refs
//     }
//
//     fn collect_fields(&mut self, fields: &'a Fields) {
//         match fields {
//             Fields::Unit => {}
//             Fields::Unnamed(u) => {
//                 for f in &u.fields {
//                     if let Some(ty) = &f.ty {
//                         self.collect_refs(ty);
//                     }
//                 }
//                 panic!("unnamed fields are not supported in Elm");
//             }
//             Fields::Named(n) => {
//                 for (_, f) in &n.fields {
//                     if let Some(ty) = &f.ty {
//                         eprintln!("field export: {:?}", ty);
//                         self.collect_refs(ty);
//                     }
//                 }
//             }
//         }
//     }
//
//     fn collect_refs(&mut self, dt: &'a DataType) {
//         match dt {
//             DataType::Primitive(_) | DataType::Generic(_) => {}
//
//             DataType::List(list) => self.collect_refs(&list.ty),
//
//             DataType::Map(map) => {
//                 self.collect_refs(map.key_ty());
//                 self.collect_refs(map.value_ty());
//             }
//
//             DataType::Tuple(tuple) => {
//                 for ty in &tuple.elements {
//                     self.collect_refs(ty);
//                 }
//             }
//
//             DataType::Nullable(inner) => self.collect_refs(inner),
//
//             DataType::Intersection(types) => {
//                 for t in types {
//                     self.collect_refs(t);
//                 }
//             }
//
//             DataType::Struct(s) => self.collect_fields(&s.fields),
//
//             DataType::Enum(e) => {
//                 for (_, variant) in &e.variants {
//                     self.collect_fields(&variant.fields);
//                 }
//             }
//
//             DataType::Reference(reference) => match reference {
//                 Reference::Named(nref) => match &nref.inner {
//                     // stdlib "named" wrappers around primitives (String, CString, OsString, ...)
//                     // aren't real declarations — recurse into the inline body and don't pool them.
//                     NamedReferenceType::Inline { dt, .. } => self.collect_refs(dt),
//                     NamedReferenceType::Reference { generics, .. } => {
//                         // panic!("Elm don't like generics");
//                         // self.pool.insert(nref);
//                         if !generics.is_empty() {
//                             panic!("NO GENERICSS!!");
//                         }
//                     }
//                     NamedReferenceType::Recursive(_) => {
//                         panic!("dont recurseee!!")
//                         // self.pool.insert(nref);
//                     }
//                 },
//                 Reference::Opaque(_) => panic!("we don't like opaque refs"),
//             },
//         }
//     }
// }
//
// }}}
// Utils: file managing {{{
fn collect_existing_files(root: &Path) -> Result<HashSet<PathBuf>, Error> {
    if !root.exists() {
        return Ok(HashSet::new());
    }

    let mut files = HashSet::new();
    let entries =
        std::fs::read_dir(root).map_err(|source| Error::read_dir(root.to_path_buf(), source))?;
    for entry in entries {
        let entry = entry.map_err(|source| Error::read_dir(root.to_path_buf(), source))?;
        let path = entry.path();
        let file_type = entry
            .file_type()
            .map_err(|source| Error::metadata(path.clone(), source))?;

        if file_type.is_symlink() {
            continue;
        }

        if file_type.is_dir() {
            files.extend(collect_existing_files(&path)?);
        } else if matches!(path.extension().and_then(|e| e.to_str()), Some(EXTENSION)) {
            files.insert(path);
        }
    }

    Ok(files)
}

fn is_generated_specta_file(path: &Path) -> Result<bool, Error> {
    match std::fs::read_to_string(path) {
        Ok(contents) => {
            Ok((contents.contains("generated by Specta")) || contents.contains(PRELUDE))
        }
        Err(err) if err.kind() == std::io::ErrorKind::InvalidData => Ok(false),
        Err(source) => Err(Error::read_file(path.to_path_buf(), source)),
    }
}

/// Remove empty directories recursively, stopping at the root
fn remove_empty_dirs(path: &Path, root: &Path) -> Result<(), Error> {
    let entries =
        std::fs::read_dir(path).map_err(|source| Error::read_dir(path.to_path_buf(), source))?;
    for entry in entries {
        let entry = entry.map_err(|source| Error::read_dir(path.to_path_buf(), source))?;
        let entry_path = entry.path();
        let file_type = entry
            .file_type()
            .map_err(|source| Error::metadata(entry_path.clone(), source))?;
        if file_type.is_symlink() {
            continue;
        }
        if file_type.is_dir() {
            remove_empty_dirs(&entry_path, root)?;
        }
    }

    let is_empty = path
        .read_dir()
        .map_err(|source| Error::read_dir(path.to_path_buf(), source))?
        .next()
        .is_none();

    if path != root && is_empty {
        match std::fs::remove_dir(path) {
            Ok(()) => {}
            Err(err) if err.kind() == std::io::ErrorKind::NotFound => {}
            Err(source) => {
                return Err(Error::remove_dir(path.to_path_buf(), source));
            }
        }
    }
    Ok(())
}

// }}}