import { Rule } from "./rule.ts";
import { PairElts, StructOfArr } from "./types.ts";
import { Extractor } from "./extractor.ts"
import { split_once } from "./utils.ts";

export function extr<A extends string[]>(...args: A): Extractor<StructOfArr<PairElts<A>, string>> {
    const seps = [] as string[];
    const vars = [] as string[];

    let pair = true;
    for (const arg of args) {
        if (pair) seps.push(arg);
        else vars.push(arg);
        pair = !pair;
    }

    const vars_ = vars as PairElts<A>;
    const rule = new Rule(seps, vars_);
    return new Extractor(text => rule.get(text))
}

Deno.test("extr_types", async () => {
    const { assertEquals } = await import("https://deno.land/std@0.224.0/assert/assert_equals.ts");
    const vars = extr()
        .or(extr("bonjour, ", 'animal', ", poilu"))
        .or(extr("bonjour, ", 'arbre', ", feuillu"))
        .get("bonjour, le chêne, feuillu");
    assertEquals({ vars }, { vars: { "arbre": "le chêne" } })
})

type ArrForDef<D extends string> =
    D extends "" ? [] :
    D extends `${infer W extends string}{{${infer V extends string}}}${infer R extends string}` ? [W, V, ...ArrForDef<R>] :
    D extends `${infer W extends string}` ? [W] :
    never;

export function def<D extends string>(def: D): Extractor<StructOfArr<PairElts<ArrForDef<D>>, string>> {
    const result = [] as string[];
    let rest = def as string;
    while (true) {
        const [word, var_rest] = split_once(rest, "{{");
        if (var_rest === null) break;
        const [var_, rest_] = split_once(var_rest, "}}");
        if (rest_ === null) throw new Error(`Invalid rule near '${rest}'`);
        result.push(word, var_);
        rest = rest_;
    }
    if (rest.length > 0) result.push(rest);
    const args = result as ArrForDef<D>;
    return extr(...args);
}

Deno.test("def_types", async () => {
    const { assertEquals } = await import("https://deno.land/std@0.224.0/assert/assert_equals.ts");
    const vars = extr()
        .or(def("bonjour, {{animal}}, poilu"))
        .or(def("bonjour, {{arbre}}, feuillu"))
        .get("bonjour, le chêne, feuillu");
    assertEquals({ vars }, { vars: { "arbre": "le chêne" } })
})