#!/usr/bin/env node

import assert from "node:assert/strict";
import * as fs from "node:fs";
import {parseArgs} from "node:util";

import SwaggerParser from "@apidevtools/swagger-parser";
import * as Diff from "diff";
import ExampleValidator from "openapi-examples-validator";
import {format as prettierFormat} from "prettier";
import {CST, Composer, LineCounter, Parser, Scalar, YAMLMap, YAMLSeq, visit} from "yaml";

const usage = "Usage: check-openapi.ts [--fix] <file>...";
const {
    values: {fix, help},
    positionals: files,
} = parseArgs({options: {fix: {type: "boolean"}, help: {type: "boolean"}}, allowPositionals: true});

if (help) {
    console.log(usage);
    process.exit(0);
}

async function checkFile(file: string): Promise<void> {
    const yaml = await fs.promises.readFile(file, "utf8");
    const lineCounter = new LineCounter();
    const tokens = [...new Parser(lineCounter.addNewLine).parse(yaml)];
    const docs = [...new Composer().compose(tokens)];
    if (docs.length !== 1) {
        return;
    }
    const [doc] = docs;
    assert.ok(doc !== undefined);
    if (doc.errors.length > 0) {
        for (const error of doc.errors) {
            console.error("%s: %s", file, error.message);
        }
        process.exitCode = 1;
        return;
    }

    const root = doc.contents;
    if (!(root instanceof YAMLMap && root.has("openapi"))) {
        return;
    }

    let ok = true;
    const reformats = new Map<
        number,
        {value: string; context: Parameters<typeof CST.setScalarValue>[2]}
    >();
    const promises: Promise<void>[] = [];

    visit(doc, {
        Map(_key, node) {
            if (node.has("$ref") && node.items.length !== 1) {
                assert.ok(node.range);
                const {line, col} = lineCounter.linePos(node.range[0]);
                console.error("%s:%d:%d: Siblings of $ref have no effect", file, line, col);
                ok = false;
            }

            const combinator = ["allOf", "anyOf", "oneOf"].find((combinator) =>
                node.has(combinator),
            );
            if (node.has("nullable") && combinator !== undefined) {
                assert.ok(node.range);
                const {line, col} = lineCounter.linePos(node.range[0]);
                console.error(
                    `%s:%d:%d: nullable has no effect as a sibling of ${combinator}`,
                    file,
                    line,
                    col,
                );
                ok = false;
            }
        },

        Pair(_key, node) {
            if (
                node.key instanceof Scalar &&
                node.key.value === "allOf" &&
                node.value instanceof YAMLSeq &&
                node.value.items.filter(
                    (subschema) => !(subschema instanceof YAMLMap && subschema.has("$ref")),
                ).length > 1
            ) {
                assert.ok(node.value.range);
                const {line, col} = lineCounter.linePos(node.value.range[0]);
                console.error("%s:%d:%d: Too many inline allOf subschemas", file, line, col);
                ok = false;
            }

            if (
                node.key instanceof Scalar &&
                node.key.value === "description" &&
                node.value instanceof Scalar &&
                typeof node.value.value === "string"
            ) {
                const value = node.value;
                const description = node.value.value;
                promises.push(
                    (async () => {
                        let formatted = await prettierFormat(description, {
                            parser: "markdown",
                        });
                        if (
                            value.type !== Scalar.BLOCK_FOLDED &&
                            value.type !== Scalar.BLOCK_LITERAL
                        ) {
                            formatted = formatted.replace(/\n$/, "");
                        }
                        if (formatted !== description) {
                            assert.ok(value.range);
                            if (fix) {
                                reformats.set(value.range[0], {
                                    value: formatted,
                                    context: {afterKey: true},
                                });
                            } else {
                                ok = false;
                                const {line, col} = lineCounter.linePos(value.range[0]);
                                console.error(
                                    "%s:%d:%d: Format description with Prettier:",
                                    file,
                                    line,
                                    col,
                                );
                                let diff = "";
                                for (const part of Diff.diffLines(description, formatted)) {
                                    const prefix = part.added
                                        ? "\u001B[32m+"
                                        : part.removed
                                          ? "\u001B[31m-"
                                          : "\u001B[34m ";
                                    diff += prefix;
                                    diff += part.value
                                        .replace(/\n$/, "")
                                        .replaceAll("\n", "\n" + prefix);
                                    diff += "\n";
                                }
                                diff += "\u001B[0m";
                                console.error(diff);
                            }
                        }
                    })(),
                );
            }
        },
    });
    await Promise.all(promises);

    if (!ok) {
        process.exitCode = 1;
    }
    if (reformats.size > 0) {
        console.log("%s: Fixing problems", file);
        for (const token of tokens) {
            if (token.type === "document") {
                CST.visit(token, ({value}) => {
                    let reformat;
                    if (
                        CST.isScalar(value) &&
                        (reformat = reformats.get(value.offset)) !== undefined
                    ) {
                        CST.setScalarValue(value, reformat.value, reformat.context);
                    }
                });
            }
        }
        await fs.promises.writeFile(file, tokens.map((token) => CST.stringify(token)).join(""));
    }

    try {
        await SwaggerParser.validate(file);
    } catch (error) {
        if (!(error instanceof SyntaxError)) {
            throw error;
        }
        console.error("%s: %s", file, error.message);
        process.exitCode = 1;
    }
    const res = await ExampleValidator.validateFile(file);
    if (!res.valid) {
        for (const error of res.errors) {
            console.error(error);
        }
        process.exitCode = 1;
    }
}

for (const file of files) {
    await checkFile(file);
}