import type { JSONContent } from '@tiptap/core';
import { Markdown, MarkdownManager } from '@tiptap/markdown';
import StarterKit from '@tiptap/starter-kit';
import { h } from 'vue';
import type { VNodeChild } from 'vue';

export function safeDescriptionLink(value: unknown): string | null {
    if (
        typeof value !== 'string' ||
        /[\s\\]/u.test(value) ||
        [...value].some(
            (character) =>
                character.charCodeAt(0) < 32 || character.charCodeAt(0) === 127,
        )
    ) {
        return null;
    }
    if (/^(https?:\/\/|mailto:)/i.test(value)) {
        try {
            const url = new URL(value);
            return ['http:', 'https:', 'mailto:'].includes(url.protocol)
                ? value
                : null;
        } catch {
            return null;
        }
    }
    return /^(\/(?!\/)|#)/.test(value) ? value : null;
}

export function descriptionExtensions() {
    return [
        StarterKit.configure({
            underline: false,
            trailingNode: false,
            link: {
                openOnClick: false,
                autolink: false,
                isAllowedUri: (url) => safeDescriptionLink(url) !== null,
                HTMLAttributes: {
                    rel: 'noopener noreferrer',
                    target: '_blank',
                },
            },
        }),
        Markdown.configure({ markedOptions: { gfm: true, breaks: true } }),
    ];
}

const markdown = new MarkdownManager({
    extensions: descriptionExtensions(),
    markedOptions: { gfm: true, breaks: true },
});

/** Unsupported Markdown stays editable verbatim instead of being silently discarded. */
export function supportsVisualDescription(value: string): boolean {
    let supported = true;
    markdown.instance.walkTokens(markdown.instance.lexer(value), (token) => {
        if (
            ['html', 'table', 'image'].includes(token.type) ||
            (token.type === 'list_item' && token.task) ||
            (token.type === 'link' && !safeDescriptionLink(token.href))
        ) {
            supported = false;
        }
    });
    return supported;
}

export function parseDescription(value: string): JSONContent {
    return markdown.parse(value);
}

/** Build Vue nodes from an explicit schema; never insert user-provided HTML. */
export function renderDescriptionNode(node: JSONContent): VNodeChild {
    if (node.type === 'text') {
        let content: VNodeChild = node.text ?? '';
        for (const mark of node.marks ?? []) {
            const tag = {
                bold: 'strong',
                italic: 'em',
                strike: 's',
                code: 'code',
            }[mark.type];
            if (tag) {
                content = h(tag, {}, [content]);
            } else if (mark.type === 'link') {
                const href = safeDescriptionLink(mark.attrs?.href);
                if (href) {
                    content = h(
                        'a',
                        { href, target: '_blank', rel: 'noopener noreferrer' },
                        [content],
                    );
                }
            }
        }
        return content;
    }
    const children = (node.content ?? []).map(renderDescriptionNode);
    switch (node.type) {
        case 'doc':
            return children;
        case 'paragraph':
            return h('p', {}, children);
        case 'heading':
            return h(
                `h${Math.min(6, Math.max(1, Number(node.attrs?.level) || 1))}`,
                {},
                children,
            );
        case 'bulletList':
            return h('ul', {}, children);
        case 'orderedList':
            return h('ol', { start: Number(node.attrs?.start) || 1 }, children);
        case 'listItem':
            return h('li', {}, children);
        case 'blockquote':
            return h('blockquote', {}, children);
        case 'codeBlock':
            return h('pre', {}, [h('code', {}, children)]);
        case 'hardBreak':
            return h('br');
        case 'horizontalRule':
            return h('hr');
        default:
            return children;
    }
}