use std::io::Write;
use itertools::Itertools;
use crate::data::RPC;
use super::IndentedWriter;

fn output_common(f: &mut IndentedWriter) {
    f.f.write_all(
b"interface _WSResponse {
    id: number;
    data: any;
}

interface _WSWaitingEntry {
    ok: (v: any) => void;
    err: (reason?: any) => void;
}

export class MRPCConnector {
    url: string;
    socket: WebSocket;
    next_message_id: number;
    waiting: { [id: number]: _WSWaitingEntry };
    streams: { [id: number]: (v: any) => void };

    private open() {
        this.socket = new WebSocket(this.url);
        this.socket.onmessage = ev => {
            const data = JSON.parse(ev.data) as _WSResponse;
            if (data.id in this.streams) {
                this.streams[data.id](data.data);
                if (data.data == null)
                    delete this.streams[data.id];
            } else if (data.id in this.waiting) {
                this.waiting[data.id].ok(data.data);
                delete this.waiting[data.id];
            } else {
                console.log(`Got unexpected message: ${data}`);
            }
        }
        this.socket.onerror = () => setTimeout(() => {this.open();}, 2500);
        this.socket.onclose = () => setTimeout(() => {this.open();}, 2500);
    }

    public constructor(url: string) {
        this.url = url;
        this.next_message_id = 0;
        this.waiting = {};
        this.streams = {};
        this.open();
    }\n\n").unwrap();
    f.ident = 1;
}

fn field_ty_to_ty_str(ty: &crate::data::FieldTy, with_name: bool) -> String {
    use crate::data::Types;

    let mut ret = String::new();
    if with_name {
        ret += &ty.name;
        if ty.optional {
            ret += "?";
        }
        ret += ": ";
    }
    ret += match &ty.ty {
        Types::String => "string",
        Types::Bool => "boolean",
        Types::F32 | Types::F64
        |Types::I8 | Types::I16 | Types::I32 | Types::I64
        |Types::U8 | Types::U16 | Types::U32 | Types::U64 => "number",
        Types::Named(name) => name
    };
    if ty.array {
        ret += "[]";
    }
    ret
}

fn output_services(f: &mut IndentedWriter, rpc: &RPC) {
    for service in &rpc.services {
        for method in &service.methods {
            write!(f, "public {}_{}(", service.name, method.name).unwrap();
            f.write_all(method.args.iter()
                .map(|arg| field_ty_to_ty_str(arg, true))
                .chain(method.ret_stream.then(|| format!("cbk: (v: {}) => void", field_ty_to_ty_str(method.ret.as_ref().unwrap(), false))))
                .join(", ")
                .as_bytes()
            ).unwrap();
            f.write_all(b")").unwrap();
            if let Some(ret) = &method.ret {
                if ret.optional {
                    unimplemented!("Optional return value is current not supported in typescript client");
                }
                if !method.ret_stream {
                    write!(f, ": Promise<{}>", field_ty_to_ty_str(ret, false)).unwrap();
                }
            }
            f.write_all(b" {\nconst msg = {id:this.next_message_id++,").unwrap();
            write!(f, "service:'{}',method:'{}',data:{{", service.name, method.name).unwrap();
            f.write_all(method.args.iter()
                .map(|arg| {
                    if arg.optional {
                        format!("{0}:{0}||null", arg.name)
                    } else {
                        arg.name.clone()
                    }
                })
                .join(",")
                .as_bytes()
            ).unwrap();
            f.write_all(b"}};\n").unwrap();
            if let Some(ret) = &method.ret {
                if !method.ret_stream {
                    writeln!(f, "const p = new Promise<{}>((ok,err) => {{ this.waiting[msg.id] = {{ ok, err }}; }});", field_ty_to_ty_str(ret, false)).unwrap();
                } else {
                    f.write_all(b"this.streams[msg.id] = cbk;\n").unwrap();
                }
            }
            f.write_all(b"this.socket.send(JSON.stringify(msg));\n").unwrap();
            if method.ret.is_some() && !method.ret_stream{
                f.write_all(b"return p;\n").unwrap();
            }
            f.write_all(b"}\n\n").unwrap();
        }
    }
    f.write_all(b"}").unwrap();
}

fn output_enums(f: &mut IndentedWriter, rpc: &RPC) {
    for e in &rpc.enums {
        writeln!(f, "export enum {} {{", e.name).unwrap();
        for (k, v) in &e.values {
            writeln!(f, "{k} = {v},").unwrap();
        }
        f.write_all(b"}\n\n").unwrap();
    }
}

fn output_structs(f: &mut IndentedWriter, rpc: &RPC) {
    for s in &rpc.structs {
        writeln!(f, "export interface {} {{", s.name).unwrap();
        for field in &s.fields {
            writeln!(f, "{};", field_ty_to_ty_str(field, true)).unwrap();
        }
        f.write_all(b"}\n\n").unwrap();
    }
}

pub fn gen(file_base_name: &std::path::PathBuf, rpc: &RPC) {
    let f = std::fs::File::create(file_base_name.with_extension("ts")).unwrap();
    let mut f = IndentedWriter::new(f);
    let f = &mut f;
    output_enums(f, rpc);
    output_structs(f, rpc);
    output_common(f);
    output_services(f, rpc);
}