/**
 * @fileoverview Rule to enforce languages for fenced code.
 * @author Nicholas C. Zakas
 */
//-----------------------------------------------------------------------------
// Type Definitions
//-----------------------------------------------------------------------------
/**
 * @import { MarkdownRuleDefinition } from "../types.js";
 * @typedef {"missingLanguage" | "disallowedLanguage"} FencedCodeLanguageMessageIds
 * @typedef {[{ required?: string[] }]} FencedCodeLanguageOptions
 * @typedef {MarkdownRuleDefinition<{ RuleOptions: FencedCodeLanguageOptions, MessageIds: FencedCodeLanguageMessageIds }>} FencedCodeLanguageRuleDefinition
 */
//-----------------------------------------------------------------------------
// Helpers
//-----------------------------------------------------------------------------
const fencedCodeCharacters = new Set(["`", "~"]);
//-----------------------------------------------------------------------------
// Rule Definition
//-----------------------------------------------------------------------------
export default /** @satisfies {FencedCodeLanguageRuleDefinition} */ ({
    meta: {
        type: "problem",
        docs: {
            recommended: true,
            description: "Require languages for fenced code blocks",
            url: "https://github.com/eslint/markdown/blob/main/docs/rules/fenced-code-language.md",
        },
        messages: {
            missingLanguage: "Missing code block language.",
            disallowedLanguage: 'Code block language "{{lang}}" is not allowed.',
        },
        schema: [
            {
                type: "object",
                properties: {
                    required: {
                        type: "array",
                        items: {
                            type: "string",
                        },
                        uniqueItems: true,
                    },
                },
                additionalProperties: false,
            },
        ],
        defaultOptions: [
            {
                required: [],
            },
        ],
    },
    create(context) {
        const required = new Set(context.options[0].required);
        const { sourceCode } = context;
        return {
            code(node) {
                if (!node.lang) {
                    // only check fenced code blocks
                    if (!fencedCodeCharacters.has(sourceCode.text[node.position.start.offset])) {
                        return;
                    }
                    /** @type {number} */
                    let openingCodeFenceEndOffset;
                    for (openingCodeFenceEndOffset = node.position.start.offset; fencedCodeCharacters.has(sourceCode.text[openingCodeFenceEndOffset]); openingCodeFenceEndOffset++) {
                        // Find the end offset of the opening code fence.
                    }
                    context.report({
                        loc: {
                            start: node.position.start,
                            end: {
                                line: node.position.start.line,
                                column: node.position.start.column +
                                    openingCodeFenceEndOffset -
                                    node.position.start.offset,
                            },
                        },
                        messageId: "missingLanguage",
                    });
                    return;
                }
                if (required.size && !required.has(node.lang)) {
                    const langIndex = sourceCode
                        .getText(node)
                        .indexOf(node.lang);
                    context.report({
                        loc: {
                            start: node.position.start,
                            end: {
                                line: node.position.start.line,
                                column: node.position.start.column +
                                    langIndex +
                                    node.lang.length,
                            },
                        },
                        messageId: "disallowedLanguage",
                        data: {
                            lang: node.lang,
                        },
                    });
                }
            },
        };
    },
});