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use std::collections::hash_map::HashMap;
use std::fmt::Write;

use descriptor::*;
use core::Message;
use compiler_plugin;
use code_writer::CodeWriter;
use descriptorx::*;

mod message;
mod enums;
mod rust_types_values;
mod well_known_types;
mod field;
mod extensions;
mod ident;

use self::message::*;
use self::enums::*;
use self::extensions::*;


fn escape_byte(s: &mut String, b: u8) {
    if b == b'\n' {
        write!(s, "\\n").unwrap();
    } else if b == b'\r' {
        write!(s, "\\r").unwrap();
    } else if b == b'\t' {
        write!(s, "\\t").unwrap();
    } else if b == b'\\' || b == b'"' {
        write!(s, "\\{}", b as char).unwrap();
    } else if b == b'\0' {
        write!(s, "\\0").unwrap();
    // ASCII printable except space
    } else if b > 0x20 && b < 0x7f {
        write!(s, "{}", b as char).unwrap();
    } else {
        write!(s, "\\x{:02x}", b).unwrap();
    }
}

fn write_file_descriptor_data(file: &FileDescriptorProto, w: &mut CodeWriter) {
    let fdp_bytes = file.write_to_bytes().unwrap();
    w.write_line("static file_descriptor_proto_data: &'static [u8] = b\"\\");
    w.indented(|w| {
        const MAX_LINE_LEN: usize = 72;

        let mut s = String::new();
        for &b in &fdp_bytes {
            let prev_len = s.len();
            escape_byte(&mut s, b);
            let truncate = s.len() > MAX_LINE_LEN;
            if truncate {
                s.truncate(prev_len);
            }
            if truncate || s.len() == MAX_LINE_LEN {
                write!(s, "\\").unwrap();
                w.write_line(&s);
                s.clear();
            }
            if truncate {
                escape_byte(&mut s, b);
            }
        }
        if !s.is_empty() {
            write!(s, "\\").unwrap();
            w.write_line(&s);
            s.clear();
        }
    });
    w.write_line("\";");
    w.write_line("");
    w.lazy_static(
        "file_descriptor_proto_lazy",
        "::protobuf::descriptor::FileDescriptorProto",
    );
    w.write_line("");
    w.def_fn("parse_descriptor_proto() -> ::protobuf::descriptor::FileDescriptorProto", |w| {
        w.write_line("::protobuf::parse_from_bytes(file_descriptor_proto_data).unwrap()");
    });
    w.write_line("");
    w.pub_fn("file_descriptor_proto() -> &'static ::protobuf::descriptor::FileDescriptorProto", |w| {
        w.unsafe_expr(|w| {
            w.block("file_descriptor_proto_lazy.get(|| {", "})", |w| {
                w.write_line("parse_descriptor_proto()");
            });
        });
    });
}

fn gen_file(
    file: &FileDescriptorProto,
    _files_map: &HashMap<&str, &FileDescriptorProto>,
    root_scope: &RootScope,
) -> Option<compiler_plugin::GenResult> {
    let scope = FileScope { file_descriptor: file }.to_scope();

    if scope.get_messages().is_empty() && scope.get_enums().is_empty() &&
        file.get_extension().is_empty()
    {
        // protoc generates empty file descriptors for directories: skip them
        return None;
    }

    let mut v = Vec::new();

    {
        let mut w = CodeWriter::new(&mut v);

        w.write_generated();

        w.write_line("");
        w.write_line("use protobuf::Message as Message_imported_for_functions;");
        w.write_line(
            "use protobuf::ProtobufEnum as ProtobufEnum_imported_for_functions;",
        );

        for message in &scope.get_messages() {
            // ignore map entries, because they are not used in map fields
            if message.map_entry().is_none() {
                w.write_line("");
                MessageGen::new(message, &root_scope).write(&mut w);
            }
        }
        for enum_type in &scope.get_enums() {
            w.write_line("");
            EnumGen::new(enum_type, file).write(&mut w);
        }

        write_extensions(file, &root_scope, &mut w);

        if file.get_options().get_optimize_for() != FileOptions_OptimizeMode::LITE_RUNTIME {
            w.write_line("");
            write_file_descriptor_data(file, &mut w);
        }
    }

    Some(compiler_plugin::GenResult {
        name: format!("{}.rs", proto_path_to_rust_mod(file.get_name())),
        content: v,
    })
}

// This function is also used externally by cargo plugin
// https://github.com/plietar/rust-protobuf-build
// So be careful changing its signature.
pub fn gen(
    file_descriptors: &[FileDescriptorProto],
    files_to_generate: &[String],
) -> Vec<compiler_plugin::GenResult> {
    let root_scope = RootScope { file_descriptors: file_descriptors };

    let mut results: Vec<compiler_plugin::GenResult> = Vec::new();
    let files_map: HashMap<&str, &FileDescriptorProto> =
        file_descriptors.iter().map(|f| (f.get_name(), f)).collect();

    let all_file_names: Vec<&str> = file_descriptors.iter().map(|f| f.get_name()).collect();

    for file_name in files_to_generate {
        let file = files_map.get(&file_name[..]).expect(&format!(
            "file not found in file descriptors: {:?}, files: {:?}",
            file_name,
            all_file_names
        ));
        results.extend(gen_file(file, &files_map, &root_scope));
    }
    results
}

pub fn protoc_gen_rust_main() {
    compiler_plugin::plugin_main(gen);
}