/**
 * Markdown toolbar helpers for text editors.
 */

/**
 * Result of a toolbar operation.
 */
export interface ToolbarResult {
  newText: string;
  newSelectionStart: number;
  newSelectionEnd: number;
}

/**
 * Apply markdown formatting to selected text.
 * If no selection, inserts before/after at cursor position.
 */
export function applyMarkdownWrap(
  text: string,
  selectionStart: number,
  selectionEnd: number,
  before: string,
  after: string = ""
): ToolbarResult {
  const selectedText = text.substring(selectionStart, selectionEnd);

  let newText: string;
  let newSelectionStart: number;
  let newSelectionEnd: number;

  if (selectedText) {
    // Wrap selected text
    newText = text.substring(0, selectionStart) + before + selectedText + after + text.substring(selectionEnd);
    newSelectionStart = selectionStart + before.length + selectedText.length + after.length;
    newSelectionEnd = newSelectionStart;
  } else {
    // Insert at cursor position
    newText = text.substring(0, selectionStart) + before + after + text.substring(selectionEnd);
    newSelectionStart = selectionStart + before.length;
    newSelectionEnd = newSelectionStart;
  }

  return { newText, newSelectionStart, newSelectionEnd };
}

/**
 * Apply wiki link formatting to selected text.
 * If no selection, inserts [[text]] with cursor between brackets.
 */
export function applyWikiLink(
  text: string,
  selectionStart: number,
  selectionEnd: number
): ToolbarResult {
  const selectedText = text.substring(selectionStart, selectionEnd);

  let newText: string;
  let newSelectionStart: number;
  let newSelectionEnd: number;

  if (selectedText) {
    // Wrap selected text with [[...]]
    newText = text.substring(0, selectionStart) + "[[" + selectedText + "]]" + text.substring(selectionEnd);
    newSelectionStart = selectionStart + 2 + selectedText.length + 2;
    newSelectionEnd = newSelectionStart;
  } else {
    // Insert [[text]] with cursor between brackets
    newText = text.substring(0, selectionStart) + "[[text]]" + text.substring(selectionEnd);
    newSelectionStart = selectionStart + 2;
    newSelectionEnd = selectionStart + 6; // Select "text"
  }

  return { newText, newSelectionStart, newSelectionEnd };
}

/**
 * Apply rel:type link formatting (for inline edge type assignment).
 * Format: [[rel:edgeType|link]]
 * If no selection, inserts [[rel:type|text]] with cursor between brackets.
 */
export function applyRelLink(
  text: string,
  selectionStart: number,
  selectionEnd: number,
  edgeType: string
): ToolbarResult {
  const selectedText = text.substring(selectionStart, selectionEnd);

  let newText: string;
  let newSelectionStart: number;
  let newSelectionEnd: number;

  if (selectedText) {
    // Wrap selected text with [[rel:type|...]]
    const relLink = `[[rel:${edgeType}|${selectedText}]]`;
    newText = text.substring(0, selectionStart) + relLink + text.substring(selectionEnd);
    newSelectionStart = selectionStart + relLink.length;
    newSelectionEnd = newSelectionStart;
  } else {
    // Insert [[rel:type|text]] with cursor between brackets
    const relLink = `[[rel:${edgeType}|text]]`;
    newText = text.substring(0, selectionStart) + relLink + text.substring(selectionEnd);
    // Select "text" part for easy editing
    newSelectionStart = selectionStart + relLink.indexOf("|") + 1;
    newSelectionEnd = selectionStart + 4; // Select "text"
  }

  return { newText, newSelectionStart, newSelectionEnd };
}

/**
 * Apply heading prefix to current line(s).
 * Toggles heading if already present.
 * Always operates on complete lines, even for partial selections.
 * Never deletes text content.
 */
export function applyHeading(
  text: string,
  selectionStart: number,
  selectionEnd: number,
  level: 2 | 3
): ToolbarResult {
  const prefix = "#".repeat(level) + " ";
  
  // Find line boundaries: operate on complete lines touched by selection
  // startLine: beginning of first line touched by selection
  const startLine = selectionStart > 0 
    ? text.lastIndexOf("\n", selectionStart - 1) + 1 
    : 0;
  
  // effectiveEnd: if selection ends at newline, don't include next line
  const effectiveEnd = (selectionEnd > 0 && text[selectionEnd - 1] === "\n") 
    ? selectionEnd - 1 
    : selectionEnd;
  
  // endLine: end of last line touched by selection (including newline if present)
  const nextNewline = text.indexOf("\n", effectiveEnd);
  const endLine = nextNewline >= 0 ? nextNewline + 1 : text.length;

  // Extract the complete block of lines to edit
  const block = text.substring(startLine, endLine);
  const lines = block.split("\n");

  // Check if all non-empty lines have the exact same heading prefix as requested
  // Must match exactly (e.g., "## " not "### " or "# ")
  const nonEmptyLines = lines.filter((line) => line.trim());
  const hasSameHeading = nonEmptyLines.length > 0 && 
    nonEmptyLines.every((line) => {
      const trimmed = line.trim();
      // Check if line starts with exactly the requested prefix
      // Match the heading pattern and compare to requested prefix
      const headingMatch = trimmed.match(/^(#+\s)/);
      return headingMatch && headingMatch[1] === prefix;
    });

  let newText: string;
  let newSelectionStart: number;
  let newSelectionEnd: number;

  if (hasSameHeading) {
    // Toggle: Remove heading prefix from ALL lines if they match the requested level
    const unprefixedLines = lines.map((line) => {
      if (line.trim()) {
        const trimmed = line.trim();
        // Check if line has exactly the requested heading prefix
        const headingMatch = trimmed.match(/^(#+\s)/);
        if (headingMatch && headingMatch[1] === prefix) {
          // Remove the matching heading prefix, preserve indentation
          const indentMatch = line.match(/^(\s*)/);
          const indent = indentMatch?.[1] ?? "";
          // Remove the prefix (e.g., "## ")
          const content = trimmed.substring(prefix.length);
          return indent + content;
        }
      }
      return line; // Empty lines or lines without matching prefix stay as-is
    });
    
    const newBlock = unprefixedLines.join("\n");
    newText = text.substring(0, startLine) + newBlock + text.substring(endLine);
    newSelectionStart = startLine;
    newSelectionEnd = startLine + newBlock.length;
  } else {
    // Add or replace heading prefix: remove any existing heading, then add new one
    const prefixedLines = lines.map((line) => {
      if (line.trim()) {
        // Preserve indentation
        const indentMatch = line.match(/^(\s*)/);
        const indent = indentMatch?.[1] ?? "";
        // Get content without indentation
        const withoutIndent = line.substring(indent.length);
        // Remove any existing heading prefix (one or more # followed by space)
        // Use a more robust regex that handles multiple spaces
        const content = withoutIndent.replace(/^#+\s+/, "").trimStart();
        // Ensure we have content (not just whitespace)
        if (content) {
          return indent + prefix + content;
        }
        // If content is empty after removing heading, return original line
        return line;
      }
      return line; // Preserve empty lines
    });
    
    const newBlock = prefixedLines.join("\n");
    newText = text.substring(0, startLine) + newBlock + text.substring(endLine);
    newSelectionStart = startLine;
    newSelectionEnd = startLine + newBlock.length;
  }

  return { newText, newSelectionStart, newSelectionEnd };
}

/**
 * Apply bullet list prefix to selected lines.
 * Toggles bullets if already present.
 * Always operates on complete lines, even for partial selections.
 */
export function applyBullets(
  text: string,
  selectionStart: number,
  selectionEnd: number
): ToolbarResult {
  const prefix = "- ";
  
  // Find line boundaries: operate on complete lines touched by selection
  // startLine: beginning of first line touched by selection
  const startLine = selectionStart > 0 
    ? text.lastIndexOf("\n", selectionStart - 1) + 1 
    : 0;
  
  // effectiveEnd: if selection ends at newline, don't include next line
  const effectiveEnd = (selectionEnd > 0 && text[selectionEnd - 1] === "\n") 
    ? selectionEnd - 1 
    : selectionEnd;
  
  // endLine: end of last line touched by selection (including newline if present)
  const nextNewline = text.indexOf("\n", effectiveEnd);
  const endLine = nextNewline >= 0 ? nextNewline + 1 : text.length;

  // Extract the complete block of lines to edit
  const block = text.substring(startLine, endLine);
  const lines = block.split("\n");

  // Check if all non-empty lines have bullet prefix
  const nonEmptyLines = lines.filter((line) => line.trim());
  const hasBullets = nonEmptyLines.length > 0 && 
    nonEmptyLines.every((line) => {
      const trimmed = line.trim();
      return trimmed.startsWith(prefix.trim());
    });

  let newText: string;
  let newSelectionStart: number;
  let newSelectionEnd: number;

  if (hasBullets) {
    // Remove bullet prefix from all lines
    const unprefixedLines = lines.map((line) => {
      const trimmed = line.trim();
      if (trimmed.startsWith(prefix.trim())) {
        // Remove prefix, preserve indentation
        const indentMatch = line.match(/^(\s*)/);
        const indent = indentMatch?.[1] ?? "";
        return indent + trimmed.substring(prefix.length);
      }
      return line; // Empty lines or lines without prefix stay as-is
    });
    
    const newBlock = unprefixedLines.join("\n");
    newText = text.substring(0, startLine) + newBlock + text.substring(endLine);
    newSelectionStart = startLine;
    newSelectionEnd = startLine + newBlock.length;
  } else {
    // Add bullet prefix to each non-empty line
    const prefixedLines = lines.map((line) => {
      if (line.trim()) {
        // Preserve indentation
        const indentMatch = line.match(/^(\s*)/);
        const indent = indentMatch?.[1] ?? "";
        const content = line.substring(indent.length);
        return indent + prefix + content;
      }
      return line; // Preserve empty lines
    });
    
    const newBlock = prefixedLines.join("\n");
    newText = text.substring(0, startLine) + newBlock + text.substring(endLine);
    newSelectionStart = startLine;
    newSelectionEnd = startLine + newBlock.length;
  }

  return { newText, newSelectionStart, newSelectionEnd };
}

/**
 * Apply numbered list prefix to selected lines.
 * Toggles numbered list if already present.
 * Always operates on complete lines, even for partial selections.
 */
export function applyNumberedList(
  text: string,
  selectionStart: number,
  selectionEnd: number
): ToolbarResult {
  // Find line boundaries: operate on complete lines touched by selection
  // startLine: beginning of first line touched by selection
  const startLine = selectionStart > 0 
    ? text.lastIndexOf("\n", selectionStart - 1) + 1 
    : 0;
  
  // effectiveEnd: if selection ends at newline, don't include next line
  const effectiveEnd = (selectionEnd > 0 && text[selectionEnd - 1] === "\n") 
    ? selectionEnd - 1 
    : selectionEnd;
  
  // endLine: end of last line touched by selection (including newline if present)
  const nextNewline = text.indexOf("\n", effectiveEnd);
  const endLine = nextNewline >= 0 ? nextNewline + 1 : text.length;

  // Extract the complete block of lines to edit
  const block = text.substring(startLine, endLine);
  const lines = block.split("\n");

  // Check if all non-empty lines have numbered prefix
  const nonEmptyLines = lines.filter((line) => line.trim());
  const hasNumbers = nonEmptyLines.length > 0 && 
    nonEmptyLines.every((line) => {
      const trimmed = line.trim();
      return /^\d+\.\s/.test(trimmed);
    });

  let newText: string;
  let newSelectionStart: number;
  let newSelectionEnd: number;

  if (hasNumbers) {
    // Remove numbered prefix from all lines
    const unprefixedLines = lines.map((line) => {
      const trimmed = line.trim();
      const match = trimmed.match(/^(\d+\.\s)(.*)$/);
      if (match) {
        // Preserve indentation
        const indentMatch = line.match(/^(\s*)/);
        const indent = indentMatch?.[1] ?? "";
        return indent + match[2];
      }
      return line; // Empty lines or lines without prefix stay as-is
    });
    
    const newBlock = unprefixedLines.join("\n");
    newText = text.substring(0, startLine) + newBlock + text.substring(endLine);
    newSelectionStart = startLine;
    newSelectionEnd = startLine + newBlock.length;
  } else {
    // Add numbered prefix to each non-empty line
    let counter = 1;
    const prefixedLines = lines.map((line) => {
      if (line.trim()) {
        // Preserve indentation
        const indentMatch = line.match(/^(\s*)/);
        const indent = indentMatch?.[1] ?? "";
        const content = line.substring(indent.length);
        return indent + `${counter++}. ${content}`;
      }
      return line; // Preserve empty lines (do not number blank lines)
    });
    
    const newBlock = prefixedLines.join("\n");
    newText = text.substring(0, startLine) + newBlock + text.substring(endLine);
    newSelectionStart = startLine;
    newSelectionEnd = startLine + newBlock.length;
  }

  return { newText, newSelectionStart, newSelectionEnd };
}

/**
 * Apply toolbar operation to textarea.
 */
function applyToTextarea(
  textarea: HTMLTextAreaElement,
  result: ToolbarResult
): void {
  textarea.value = result.newText;
  textarea.setSelectionRange(result.newSelectionStart, result.newSelectionEnd);
  textarea.focus();
  textarea.dispatchEvent(new Event("input", { bubbles: true }));
}

/**
 * Create markdown toolbar with buttons.
 */
export function createMarkdownToolbar(
  textarea: HTMLTextAreaElement,
  onTogglePreview?: () => void,
  onPickNote?: (app: any) => void
): HTMLElement {
  const toolbar = document.createElement("div");
  toolbar.className = "markdown-toolbar";
  toolbar.style.display = "flex";
  toolbar.style.gap = "0.25em";
  toolbar.style.padding = "0.5em";
  toolbar.style.borderBottom = "1px solid var(--background-modifier-border)";
  toolbar.style.flexWrap = "wrap";
  toolbar.style.alignItems = "center";

  // Bold
  const boldBtn = createToolbarButton("B", "Bold (Ctrl+B)", () => {
    const result = applyMarkdownWrap(
      textarea.value,
      textarea.selectionStart,
      textarea.selectionEnd,
      "**",
      "**"
    );
    applyToTextarea(textarea, result);
  });
  toolbar.appendChild(boldBtn);

  // Italic
  const italicBtn = createToolbarButton("I", "Italic (Ctrl+I)", () => {
    const result = applyMarkdownWrap(
      textarea.value,
      textarea.selectionStart,
      textarea.selectionEnd,
      "*",
      "*"
    );
    applyToTextarea(textarea, result);
  });
  toolbar.appendChild(italicBtn);

  // H2
  const h2Btn = createToolbarButton("H2", "Heading 2", () => {
    const result = applyHeading(
      textarea.value,
      textarea.selectionStart,
      textarea.selectionEnd,
      2
    );
    applyToTextarea(textarea, result);
  });
  toolbar.appendChild(h2Btn);

  // H3
  const h3Btn = createToolbarButton("H3", "Heading 3", () => {
    const result = applyHeading(
      textarea.value,
      textarea.selectionStart,
      textarea.selectionEnd,
      3
    );
    applyToTextarea(textarea, result);
  });
  toolbar.appendChild(h3Btn);

  // Bullet List
  const bulletBtn = createToolbarButton("•", "Bullet List", () => {
    const result = applyBullets(
      textarea.value,
      textarea.selectionStart,
      textarea.selectionEnd
    );
    applyToTextarea(textarea, result);
  });
  toolbar.appendChild(bulletBtn);

  // Numbered List
  const numberedBtn = createToolbarButton("1.", "Numbered List", () => {
    const result = applyNumberedList(
      textarea.value,
      textarea.selectionStart,
      textarea.selectionEnd
    );
    applyToTextarea(textarea, result);
  });
  toolbar.appendChild(numberedBtn);

  // Code
  const codeBtn = createToolbarButton("</>", "Code (Ctrl+`)", () => {
    const result = applyMarkdownWrap(
      textarea.value,
      textarea.selectionStart,
      textarea.selectionEnd,
      "`",
      "`"
    );
    applyToTextarea(textarea, result);
  });
  toolbar.appendChild(codeBtn);

  // Link (WikiLink)
  const linkBtn = createToolbarButton("🔗", "Wiki Link", () => {
    const result = applyWikiLink(
      textarea.value,
      textarea.selectionStart,
      textarea.selectionEnd
    );
    applyToTextarea(textarea, result);
  });
  toolbar.appendChild(linkBtn);

  // Pick note button (if callback provided)
  if (onPickNote) {
    const pickNoteBtn = createToolbarButton("📎", "Pick note…", () => {
      // Get app from window (Obsidian exposes it globally)
      const app = (window as any).app;
      if (app && onPickNote) {
        onPickNote(app);
      } else {
        console.warn("App not available for entity picker");
      }
    });
    toolbar.appendChild(pickNoteBtn);
  }

  // Preview toggle
  if (onTogglePreview) {
    const previewBtn = createToolbarButton("👁️", "Toggle Preview", () => {
      onTogglePreview();
    });
    previewBtn.style.marginLeft = "auto";
    toolbar.appendChild(previewBtn);
  }

  return toolbar;
}

/**
 * Create a toolbar button.
 */
function createToolbarButton(
  label: string,
  title: string,
  onClick: () => void
): HTMLElement {
  const button = document.createElement("button");
  button.textContent = label;
  button.title = title;
  button.className = "markdown-toolbar-button";
  button.style.padding = "0.25em 0.5em";
  button.style.border = "1px solid var(--background-modifier-border)";
  button.style.borderRadius = "4px";
  button.style.background = "var(--background-primary)";
  button.style.cursor = "pointer";
  button.style.fontSize = "0.9em";
  button.style.minWidth = "2em";

  button.addEventListener("click", (e) => {
    e.preventDefault();
    e.stopPropagation();
    onClick();
  });

  button.addEventListener("mouseenter", () => {
    button.style.background = "var(--interactive-hover)";
  });

  button.addEventListener("mouseleave", () => {
    button.style.background = "var(--background-primary)";
  });

  return button;
}