#![recursion_limit = "256"]

mod tokens;
mod errors;
mod tools;

extern crate proc_macro;

use proc_macro::{ TokenStream };
use proc_macro2::{ TokenStream as TokenStream2, Span as Span2 };
use std::collections::HashMap;

use lazy_static::lazy_static;
use quote::quote;
use syn::{ Ident, ItemFn, parse_macro_input };
use tokens::{ CommandToken, OptionsToken};

use crate::errors::{DON_NOT_MATCH, ENTRY_ONLY_MAIN, NO_SUB_CMD_NAMES_MAIN, OPT_DUPLICATE_DEFINITION, compile_error_info, DIRECT_ONLY_ONCE};
use crate::tools::generate_call_fn;
use crate::tokens::{PureArguments, check_arguments};
use syn::spanned::Spanned;

macro_rules! prefix {
    ($($i: tt),*) => {
        {
            let mut prefix_str = String::new();

            prefix_str.push_str("_commander_rust");
            $(
                prefix_str.push_str(&format!("_{}", $i));
            )*
            prefix_str
        }
    };

    ($e: expr) => {
        {
            format!("_commander_rust_{}", $e)
        }
    }
}

macro_rules! import {
    ($o: ident as $r: ident) => {
        quote! {
            use commander_rust::{ $o as $r };
        }
    };
    ($o: ident as $r: ident from $f: path) => {
        quote! {
            use $f::{ $o as $r };
        }
    }
}

lazy_static! {
    static ref COMMAND_OPTIONS: std::sync::Mutex<HashMap<String, Vec<String>>> = std::sync::Mutex::new(HashMap::new());
    static ref OPTIONS: std::sync::Mutex<Vec<String>> = std::sync::Mutex::new(vec![]);
    static ref GET_FN_NAMES: std::sync::Mutex<Vec<String>> = std::sync::Mutex::new(vec![]);
    static ref DIRECT_NAME: std::sync::Mutex<Option<String>> = std::sync::Mutex::new(None);
}


/// Define command.
///
/// # Format
///
/// `#[command(sub_cmd $(<rs>|[os]|<rm...>|[om...]),* , desc)]`, explain:
/// - `sub_name`: the name of sub-command you defined, it should be same as the name of command processing function
/// - `$(<rs>|[os]|<rm...>|[om...]),*`: arguments list, divided by comma. Only four types of arguments: <RequiredSingle>,[OptionalSingle],<RequiredMultiple>,[OptionalMultiple]
/// - `desc`: description of this sub-command, it's using for display help information.
///
/// # Note
///
/// `#[command]` should be placed after all `#[option]`
#[proc_macro_attribute]
pub fn command(cmd: TokenStream, method: TokenStream) -> TokenStream {
    let method: ItemFn = parse_macro_input!(method as ItemFn);
    let ItemFn {
        ident,
        decl,
        ..
    } = &method;
    let name = format!("{}", ident);
    let get_fn = Ident::new(&prefix!(name), ident.span());
    let cmd_token = Ident::new(&prefix!("Command"), ident.span());
    let opts = COMMAND_OPTIONS.lock().unwrap();
    let mut get_fn_names = GET_FN_NAMES.lock().unwrap();
    let mut get_fns = vec![];

    // clear all options in OPTIONS
    OPTIONS.lock().unwrap().clear();

    if let Some(v) = opts.get(&name) {
        for i in v {
            get_fns.push(Ident::new(&prefix!(name, i), ident.span()));
        }
    }

    if !get_fn_names.contains(&name) {
        get_fn_names.push(name.clone());
    }

    let command: CommandToken = parse_macro_input!(cmd as CommandToken);
    // generating call function， because we can't call unstable (uncertain quantity parameters) function
    let call_fn_name = Ident::new(&prefix!(name, "call"), ident.span());
    let call_fn = generate_call_fn(&decl.inputs, &call_fn_name, &ident);
    let mut error_info = check_arguments(&command.args);

    if format!("{}", command.name) != "main" && format!("{}", command.name) != name {
        error_info = compile_error_info(command.name.span(), DON_NOT_MATCH);
    }

    if name == "main" {
        error_info = compile_error_info(ident.span(), NO_SUB_CMD_NAMES_MAIN)
    }

    TokenStream::from(quote! {
        #error_info

        fn #get_fn() -> #cmd_token {
            let mut command = #command;
            let mut fns = CALL_FNS.lock().unwrap();

            if !fns.contains_key(#name) {
                fns.insert(String::from(#name), #call_fn_name);
            }

            command.opts = {
                let mut v = vec![];
                #(
                    v.push(#get_fns());
                )*
                v
            };
            command
        }

        #call_fn

        #method
    })
}


/// Define option of command or public.
///
/// # Format
///
/// it's similar with `command`. The only difference between them is the length of arguments.
///
/// `#[command(sub_cmd <rs>|[os]|<rm...>|[om...] , desc)]`, explain:
/// - `sub_name`: the name of sub-command you defined, it should be same as the name of command processing function
/// - `<rs>|[os]|<rm...>|[om...]`: only one. Only four types of arguments: <RequiredSingle>,[OptionalSingle],<RequiredMultiple>,[OptionalMultiple]
/// - `desc`: description of this sub-command, it's using for display help information.
///
/// # Note
///
/// all `#[option]` should be placed before `#[command]`
///
#[proc_macro_attribute]
pub fn option(opt: TokenStream, method: TokenStream) -> TokenStream {
    let option: OptionsToken = parse_macro_input!(opt as OptionsToken);
    let method: ItemFn = parse_macro_input!(method as ItemFn);
    let ItemFn {
        ident,
        ..
    } = &method;
    let name = format!("{}", ident);
    let opt_name = format!("{}", option.long);
    let fn_name = prefix!(name, opt_name);
    let get_fn = Ident::new(&fn_name, option.long.span());
    let opt_token = Ident::new(&prefix!("Options"), ident.span());
    let mut opts = COMMAND_OPTIONS.lock().unwrap();
    let mut error_info = TokenStream2::new();
    let mut all_opts = OPTIONS.lock().unwrap();


    // check if options are duplicate definition
    if all_opts.contains(&format!("{}", option.short)) {
        error_info = compile_error_info(option.short.span(), OPT_DUPLICATE_DEFINITION);
    } else if all_opts.contains(&format!("{}", option.long)) {
        error_info = compile_error_info(option.long.span(), OPT_DUPLICATE_DEFINITION);
    } else {
        all_opts.push(format!("{}", option.short));
        all_opts.push(format!("{}", option.long));

        if opts.contains_key(&name) {
            if let Some(v) = opts.get_mut(&name) {
                v.push(opt_name);
            }
        } else {
            opts.insert(name, vec![opt_name]);
        }
    }

    if error_info.is_empty() {
        TokenStream::from(quote! {
            #error_info

            fn #get_fn() -> #opt_token {
                #option
            }

            #method
        })
    } else {
        TokenStream::from(quote! {
            #error_info

            #method
        })
    }

}

/// Define direct function of CLI
///
/// It allows users that don't use sub-command. It can be used directly.
///
/// # example
///
/// ```ignore
/// #[direct(<a> <b> [c] [d])]
///  fn direct(a: String, b: String) {
///      println!("hello! {} {}", a, b);
///  }
/// ```
/// When you input `[pkg-name] 1 2 3`, cli will print "hello! 1 2".
/// So it allows you that don't need to define a sub-command anymore in some simple situations.
///
/// # Format
///
/// Only accept arguments, such as `#[direct(<a> <b> <c>)]`.

#[proc_macro_attribute]
pub fn direct(pure_args: TokenStream, func: TokenStream) -> TokenStream {
    let func: ItemFn = parse_macro_input!(func as ItemFn);
    let ItemFn {
        ident,
        decl,
        ..
    } = &func;
    let name = format!("{}", ident);
    let pure_args: PureArguments = parse_macro_input!(pure_args as PureArguments);
    let direct_fn: &mut Option<String> = &mut (*DIRECT_NAME.lock().unwrap());
    let direct_get_fn = Ident::new(&prefix!(name), ident.span());
    let argument_ident = Ident::new(&prefix!("Argument"), ident.span());
    let call_fn_name = Ident::new(&prefix!(name, "call"), ident.span());
    let call_fn = generate_call_fn(&decl.inputs, &call_fn_name, &ident);
    let mut error_info: TokenStream2 = check_arguments(&pure_args.0);


    if let Some(_) = direct_fn {
        error_info = compile_error_info(pure_args.span(), DIRECT_ONLY_ONCE);
    } else {
        *direct_fn = Some(format!("{}", ident));
    }

    TokenStream::from(quote! {
        #error_info

        #func

        fn #direct_get_fn() -> Vec<#argument_ident> {
            let direct_fn: &mut Option<fn(raws: &Vec<_commander_rust_Raw>, app: _commander_rust_Cli)> = &mut (*DIRECT_FN.lock().unwrap());

            *direct_fn.borrow_mut() = Some(#call_fn_name);
            #pure_args
        }

        #call_fn
    })
}

/// Define entry of CLI.
///
/// Only using for `main` function. No parameter needed.
///
/// # Note
///
/// If you want to define public options, put all options before `#[entry]`.
/// In other word, you can regard `#[entry]` as `#[command]` without parameters.
///
#[proc_macro_attribute]
pub fn entry(pure_arguments: TokenStream, main: TokenStream) -> TokenStream {
    let pure_args: PureArguments = parse_macro_input!(pure_arguments as PureArguments);
    let main: ItemFn = parse_macro_input!(main as ItemFn);
    let ItemFn {
        ident,
        ..
    } = &main;
    let target = format!("{}", ident);
    let opts = COMMAND_OPTIONS.lock().unwrap();
    let imports = vec![
        import!(Argument as _commander_rust_Argument),
        import!(ArgumentType as _commander_rust_ArgumentType),
        import!(Command as _commander_rust_Command),
        import!(Options as _commander_rust_Options),
        import!(Raw as _commander_rust_Raw),
        import!(normalize as _commander_rust_normalize),
        import!(Instance as _commander_rust_Instance),
        import!(ls as _commander_rust_ls),
        import!(Application as _commander_rust_Application),
        import!(Cli as _commander_rust_Cli),
    ];
    let get_fn = Ident::new(&prefix!("main"), ident.span());
    let app_token = Ident::new(&prefix!("Application"), ident.span());
    let get_fn_names = GET_FN_NAMES.lock().unwrap();
    let direct_fn = &(*DIRECT_NAME.lock().unwrap());
    let mut get_cmds_fns = vec![];
    let mut get_opts_fns = vec![];
    let mut error_info = check_arguments(&pure_args.0);

    // init can be used with fn main only
    if target != String::from("main") {
        error_info = compile_error_info(ident.span(), ENTRY_ONLY_MAIN);
    }

    if let Some(v) = opts.get("main") {
        for i in v {
            get_opts_fns.push(Ident::new(&prefix!("main", i), ident.span()));
        }
    }

    for i in get_fn_names.iter() {
        get_cmds_fns.push(Ident::new(&prefix!(i), ident.span()));
    }

    let needed = quote! {
        #error_info
        mod _commander_rust_Inner {
            use crate::_commander_rust_ls;
            use crate::_commander_rust_Raw;
            use crate::_commander_rust_Cli;

            type Raw = _commander_rust_Raw;
            type Map = std::collections::HashMap<String, fn(raws: &Vec<Raw>, app: _commander_rust_Cli)>;
            type Mutex = std::sync::Mutex<Map>;

            _commander_rust_ls! {
               pub static ref CALL_FNS: Mutex = Mutex::new(Map::new());
               pub static ref DIRECT_FN: std::sync::Mutex<Option<fn(raws: &Vec<Raw>, app: _commander_rust_Cli)>> = std::sync::Mutex::new(None);
            }

            pub const APP_NAME: &'static str = env!("CARGO_PKG_NAME");
            pub const VERSION: &'static str = env!("CARGO_PKG_VERSION");
            pub const DESCRIPTION: &'static str = env!("CARGO_PKG_DESCRIPTION");
        }

        use _commander_rust_Inner::{ CALL_FNS, DIRECT_FN, VERSION, DESCRIPTION, APP_NAME };
        #(#imports)*

        #main
    };

    // inject direct-functions' arguments or not
    if let Some(df) = direct_fn {
        let direct_get_fn = Ident::new(&prefix!(df), Span2::call_site());

        TokenStream::from(quote! {
            #needed

            fn #get_fn() -> #app_token {
                let mut application = #app_token {
                    name: String::from(APP_NAME),
                    desc: String::from(DESCRIPTION),
                    opts: vec![],
                    cmds: vec![],
                    direct_args: vec![],
                };

                application.opts = {
                    let mut v = vec![];
                    #(
                        v.push(#get_opts_fns());
                    )*
                    v
                };
                application.cmds = {
                    let mut v = vec![];
                    #(
                        v.push(#get_cmds_fns());
                    )*
                    v
                };
                // inject direct-fns
                application.direct_args = #direct_get_fn();

                application
            }
        })
    } else {
        TokenStream::from(quote!{
            #needed

            fn #get_fn() -> #app_token {
                let mut application = #app_token {
                    name: String::from(APP_NAME),
                    desc: String::from(DESCRIPTION),
                    opts: vec![],
                    cmds: vec![],
                    direct_args: vec![],
                };

                application.opts = {
                    let mut v = vec![];
                    #(
                        v.push(#get_opts_fns());
                    )*
                    v
                };

                application.cmds = {
                    let mut v = vec![];
                    #(
                        v.push(#get_cmds_fns());
                    )*
                    v
                };
                application
            }
        })
    }
}

/// Run cli now.
///
/// `run!()` instead of `run()`. You can use this macro to get application of cli.
/// See `Application` for more details.
///
#[proc_macro]
pub fn run(_: TokenStream) -> TokenStream {
    TokenStream::from(quote! {
        {
            // _commander_rust_main is generated by `entry`
            //
            let mut app = _commander_rust_main();
            let ins;

            app.derive();
            ins = _commander_rust_normalize(std::env::args().into_iter().collect::<Vec<String>>(), &app);

            let cli = _commander_rust_Cli::from(&ins, &app);
            let fns = CALL_FNS.lock().unwrap();

            if let Some(cli) = cli {
                if cli.has("help") || cli.has("h") {
                    // display sub-command usage
                    if cli.cmd.is_some() {
                        for cmd in &app.cmds {
                            if cmd.name == cli.get_name() {
                                println!("{:#?}", cmd);
                                break;
                            }
                        }
                    } else {
                        // display cli usage
                        println!("{:#?}", app);
                    }
                } else if cli.has("version") || cli.has("V") {
                    println!("version: {}", VERSION);
                } else {
                    if let Some(callback) = fns.get(&cli.get_name()) {
                        callback(&cli.get_raws(), cli);
                    } else if !cli.direct_args.is_empty() {
                        let df = *DIRECT_FN.lock().unwrap();

                        if let Some(f) = &df {
                            f(&cli.direct_args.clone(), cli)
                        } else {
                            println!("ERRRRR");
                        }
                    } else {
                        eprintln!("Unknown usage. Using `{} --help` for more help information.\n", APP_NAME);
                    }
                }
            } else {
                println!("Using `{} --help` for more help information.", APP_NAME);
            }

            app
        }
    })
}