import * as Parsing from "./parsing"
import * as state from "./state"

/** Accepts keyevents, resolves them to maps, maps to exstrs, executes exstrs */
function *ParserController () {
    while (true) {
        let ex_str = ""
        let keys = []
        try {
            while (true) { 
                let keyevent = yield
                let keypress = keyevent.key

                // Special keys (e.g. Backspace) are not handled properly
                // yet. So drop them. This also drops all modifier keys.
                // When we put in handling for other special keys, remember
                // to continue to ban modifiers.
                if (keypress.length > 1) {
                    continue
                }

                keys.push(keypress)
                let response = Parsing.normalmode.parser(keys)
                switch(state.MODE){
                    case "NORMAL":
                        response = Parsing.normalmode.parser(keys)
                        break

                    case "INSERT":
                        response = Parsing.insertmode.parser(keys)
                        break
                }

                console.debug(keys, response)

                if (response.ex_str){
                    ex_str = response.ex_str
                    break
                } else {
                    keys = response.keys
                }
            }
            acceptExCmd(ex_str)
        } catch (e) {
            // Rumsfeldian errors are caught here
            console.error("Tridactyl ParserController fatally wounded:", e)
        }
    }
}

let generator = ParserController() // var rather than let stops weirdness in repl.
generator.next()

/** Feed keys to the ParserController */
export function acceptKey(keyevent: Event) {
    generator.next(keyevent)
}

/** Parse and execute ExCmds */
export function acceptExCmd(ex_str: string) {
    let [func, args] = Parsing.exmode.parser(ex_str)

    try {
        func(...args)
    } catch (e) {
        // Errors from func are caught here (e.g. no next tab)
        // TODO: Errors should go to CommandLine.
        console.error(e)
    }
}