import fs from 'fs/promises';

export interface ChecklistItem {
    text: string;
    checked: boolean;
}

/**
 * Parses a markdown file and extracts all checkboxes.
 * Matches lines like:
 * - [ ] Task
 * - [x] Completed task
 * * [ ] Alternative bullet
 */
export function parseMarkdownChecklist(content: string): ChecklistItem[] {
    const lines = content.split('\n');
    const items: ChecklistItem[] = [];

    // Regex to match markdown checkboxes: - [ ] or - [x] or * [ ] or * [x]
    const checkboxRegex = /^[*-]\s+\[([ xX])\]\s+(.+)$/;

    for (const line of lines) {
        const trimmed = line.trim();
        const match = trimmed.match(checkboxRegex);
        if (match) {
            items.push({
                checked: match[1].toLowerCase() === 'x',
                text: match[2].trim()
            });
        }
    }

    return items;
}

/**
 * Updates a markdown file's checkboxes based on a new checklist.
 * Preserves other content.
 */
export function updateMarkdownChecklist(content: string, newChecklist: ChecklistItem[]): string {
    const lines = content.split('\n');
    const updatedLines = [...lines];
    const checkboxRegex = /^[*-]\s+\[([ xX])\]\s+(.+)$/;

    let checklistIdx = 0;

    for (let i = 0; i < updatedLines.length; i++) {
        const line = updatedLines[i];
        const match = line.match(checkboxRegex);

        if (match && checklistIdx < newChecklist.length) {
            const newItem = newChecklist[checklistIdx];
            const prefix = line.substring(0, line.indexOf('['));
            const suffix = line.substring(line.indexOf(']') + 1);

            // Note: This logic assumes the text matches. If it doesn't, we might need a better matching strategy.
            // For now, let's assume order is preserved.
            updatedLines[i] = `${prefix}[${newItem.checked ? 'x' : ' '}]${suffix}`;
            checklistIdx++;
        }
    }

    return updatedLines.join('\n');
}