import { uniq, isString } from 'lodash';

const defaultAttrs = {
  td: { colspan: 1, rowspan: 1, colwidth: null },
  th: { colspan: 1, rowspan: 1, colwidth: null },
};

const ignoreAttrs = {
  dd: ['isTerm'],
  dt: ['isTerm'],
};

const tableMap = new WeakMap();

// Source taken from
// prosemirror-markdown/src/to_markdown.js
export function isPlainURL(link, parent, index, side) {
  if (link.attrs.title || !/^\w+:/.test(link.attrs.href)) return false;
  const content = parent.child(index + (side < 0 ? -1 : 0));
  if (
    !content.isText ||
    content.text !== link.attrs.href ||
    content.marks[content.marks.length - 1] !== link
  )
    return false;
  if (index === (side < 0 ? 1 : parent.childCount - 1)) return true;
  const next = parent.child(index + (side < 0 ? -2 : 1));
  return !link.isInSet(next.marks);
}

function containsOnlyText(node) {
  if (node.childCount === 1) {
    const child = node.child(0);
    return child.isText && child.marks.length === 0;
  }

  return false;
}

function containsParagraphWithOnlyText(cell) {
  if (cell.childCount === 1) {
    const child = cell.child(0);
    if (child.type.name === 'paragraph') {
      return containsOnlyText(child);
    }
  }

  return false;
}

function getRowsAndCells(table) {
  const cells = [];
  const rows = [];
  table.descendants((n) => {
    if (n.type.name === 'tableCell' || n.type.name === 'tableHeader') {
      cells.push(n);
      return false;
    }

    if (n.type.name === 'tableRow') {
      rows.push(n);
    }

    return true;
  });
  return { rows, cells };
}

function getChildren(node) {
  const children = [];
  for (let i = 0; i < node.childCount; i += 1) {
    children.push(node.child(i));
  }
  return children;
}

export function shouldRenderHTMLTable(table) {
  const { rows, cells } = getRowsAndCells(table);

  const cellChildCount = Math.max(...cells.map((cell) => cell.childCount));
  const maxColspan = Math.max(...cells.map((cell) => cell.attrs.colspan));
  const maxRowspan = Math.max(...cells.map((cell) => cell.attrs.rowspan));

  const rowChildren = rows.map((row) => uniq(getChildren(row).map((cell) => cell.type.name)));
  const cellTypeInFirstRow = rowChildren[0];
  const cellTypesInOtherRows = uniq(rowChildren.slice(1).map(([type]) => type));

  // if the first row has headers, and there are no headers anywhere else, render markdown table
  if (
    !(
      cellTypeInFirstRow.length === 1 &&
      cellTypeInFirstRow[0] === 'tableHeader' &&
      cellTypesInOtherRows.length === 1 &&
      cellTypesInOtherRows[0] === 'tableCell'
    )
  ) {
    return true;
  }

  if (cellChildCount === 1 && maxColspan === 1 && maxRowspan === 1) {
    // if all rows contain only one paragraph each and no rowspan/colspan, render markdown table
    const children = uniq(cells.map((cell) => cell.child(0).type.name));
    if (children.length === 1 && children[0] === 'paragraph') {
      return false;
    }
  }

  return true;
}

function htmlEncode(str = '') {
  return str
    .replace(/&/g, '&amp;')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/'/g, '&#39;')
    .replace(/"/g, '&#34;');
}

export function openTag(tagName, attrs) {
  let str = `<${tagName}`;

  str += Object.entries(attrs || {})
    .map(([key, value]) => {
      if ((ignoreAttrs[tagName] || []).includes(key) || defaultAttrs[tagName]?.[key] === value)
        return '';

      return ` ${key}="${htmlEncode(value?.toString())}"`;
    })
    .join('');

  return `${str}>`;
}

export function closeTag(tagName) {
  return `</${tagName}>`;
}

function isInBlockTable(node) {
  return tableMap.get(node);
}

function isInTable(node) {
  return tableMap.has(node);
}

function setIsInBlockTable(table, value) {
  tableMap.set(table, value);

  const { rows, cells } = getRowsAndCells(table);
  rows.forEach((row) => tableMap.set(row, value));
  cells.forEach((cell) => {
    tableMap.set(cell, value);
    if (cell.childCount && cell.child(0).type.name === 'paragraph')
      tableMap.set(cell.child(0), value);
  });
}

function unsetIsInBlockTable(table) {
  tableMap.delete(table);

  const { rows, cells } = getRowsAndCells(table);
  rows.forEach((row) => tableMap.delete(row));
  cells.forEach((cell) => {
    tableMap.delete(cell);
    if (cell.childCount) tableMap.delete(cell.child(0));
  });
}

function renderTagOpen(state, tagName, attrs) {
  state.ensureNewLine();
  state.write(openTag(tagName, attrs));
}

function renderTagClose(state, tagName, insertNewline = true) {
  state.write(closeTag(tagName));
  if (insertNewline) state.ensureNewLine();
}

function renderTableHeaderRowAsMarkdown(state, node, cellWidths) {
  state.flushClose(1);

  state.write('|');
  node.forEach((cell, _, i) => {
    if (i) state.write('|');

    state.write(cell.attrs.align === 'center' ? ':' : '-');
    state.write(state.repeat('-', cellWidths[i]));
    state.write(cell.attrs.align === 'center' || cell.attrs.align === 'right' ? ':' : '-');
  });
  state.write('|');

  state.closeBlock(node);
}

function renderTableRowAsMarkdown(state, node, isHeaderRow = false) {
  const cellWidths = [];

  state.flushClose(1);

  state.write('| ');
  node.forEach((cell, _, i) => {
    if (i) state.write(' | ');

    const { length } = state.out;
    state.render(cell, node, i);
    cellWidths.push(state.out.length - length);
  });
  state.write(' |');

  state.closeBlock(node);

  if (isHeaderRow) renderTableHeaderRowAsMarkdown(state, node, cellWidths);
}

function renderTableRowAsHTML(state, node) {
  renderTagOpen(state, 'tr');

  node.forEach((cell, _, i) => {
    const tag = cell.type.name === 'tableHeader' ? 'th' : 'td';

    renderTagOpen(state, tag, cell.attrs);

    if (!containsParagraphWithOnlyText(cell)) {
      state.closeBlock(node);
      state.flushClose();
    }

    state.render(cell, node, i);
    state.flushClose(1);

    renderTagClose(state, tag);
  });

  renderTagClose(state, 'tr');
}

export function renderContent(state, node, forceRenderInline) {
  if (node.type.inlineContent) {
    if (containsOnlyText(node)) {
      state.renderInline(node);
    } else {
      state.closeBlock(node);
      state.flushClose();
      state.renderInline(node);
      state.closeBlock(node);
      state.flushClose();
    }
  } else {
    const renderInline = forceRenderInline || containsParagraphWithOnlyText(node);
    if (!renderInline) {
      state.closeBlock(node);
      state.flushClose();
      state.renderContent(node);
      state.ensureNewLine();
    } else {
      state.renderInline(forceRenderInline ? node : node.child(0));
    }
  }
}

export function renderHTMLNode(tagName, forceRenderContentInline = false) {
  return (state, node) => {
    renderTagOpen(state, tagName, node.attrs);
    renderContent(state, node, forceRenderContentInline);
    renderTagClose(state, tagName, false);

    if (forceRenderContentInline) {
      state.closeBlock(node);
      state.flushClose();
    }
  };
}

export function renderOrderedList(state, node) {
  const { parens } = node.attrs;
  const start = node.attrs.start || 1;
  const maxW = String(start + node.childCount - 1).length;
  const space = state.repeat(' ', maxW + 2);
  const delimiter = parens ? ')' : '.';

  state.renderList(node, space, (i) => {
    const nStr = String(start + i);
    return `${state.repeat(' ', maxW - nStr.length) + nStr}${delimiter} `;
  });
}

export function renderTableCell(state, node) {
  if (!isInBlockTable(node) || containsParagraphWithOnlyText(node)) {
    state.renderInline(node.child(0));
  } else {
    state.renderContent(node);
  }
}

export function renderTableRow(state, node) {
  if (isInBlockTable(node)) {
    renderTableRowAsHTML(state, node);
  } else {
    renderTableRowAsMarkdown(state, node, node.child(0).type.name === 'tableHeader');
  }
}

export function renderTable(state, node) {
  setIsInBlockTable(node, shouldRenderHTMLTable(node));

  if (isInBlockTable(node)) renderTagOpen(state, 'table');

  state.renderContent(node);

  if (isInBlockTable(node)) renderTagClose(state, 'table');

  // ensure at least one blank line after any table
  state.closeBlock(node);
  state.flushClose();

  unsetIsInBlockTable(node);
}

export function renderHardBreak(state, node, parent, index) {
  const br = isInTable(parent) ? '<br>' : '\\\n';

  for (let i = index + 1; i < parent.childCount; i += 1) {
    if (parent.child(i).type !== node.type) {
      state.write(br);
      return;
    }
  }
}

export function renderImage(state, node) {
  const { alt, canonicalSrc, src, title } = node.attrs;

  if (isString(src) || isString(canonicalSrc)) {
    const quotedTitle = title ? ` ${state.quote(title)}` : '';

    state.write(`![${state.esc(alt || '')}](${state.esc(canonicalSrc || src)}${quotedTitle})`);
  }
}

export function renderPlayable(state, node) {
  renderImage(state, node);
}

export function renderCodeBlock(state, node) {
  state.write(`\`\`\`${node.attrs.language || ''}\n`);
  state.text(node.textContent, false);
  state.ensureNewLine();
  state.write('```');
  state.closeBlock(node);
}

export function preserveUnchanged(render) {
  return (state, node, parent, index) => {
    const { sourceMarkdown } = node.attrs;
    const same = state.options.changeTracker.get(node);

    if (same) {
      state.write(sourceMarkdown);
      state.closeBlock(node);
    } else {
      render(state, node, parent, index);
    }
  };
}

const generateBoldTags = (open = true) => {
  return (_, mark) => {
    const type = /^(\*\*|__|<strong|<b).*/.exec(mark.attrs.sourceMarkdown)?.[1];

    switch (type) {
      case '**':
      case '__':
        return type;
      // eslint-disable-next-line @gitlab/require-i18n-strings
      case '<strong':
      case '<b':
        return (open ? openTag : closeTag)(type.substring(1));
      default:
        return '**';
    }
  };
};

export const bold = {
  open: generateBoldTags(),
  close: generateBoldTags(false),
  mixable: true,
  expelEnclosingWhitespace: true,
};

const generateItalicTag = (open = true) => {
  return (_, mark) => {
    const type = /^(\*|_|<em|<i).*/.exec(mark.attrs.sourceMarkdown)?.[1];

    switch (type) {
      case '*':
      case '_':
        return type;
      // eslint-disable-next-line @gitlab/require-i18n-strings
      case '<em':
      case '<i':
        return (open ? openTag : closeTag)(type.substring(1));
      default:
        return '_';
    }
  };
};

export const italic = {
  open: generateItalicTag(),
  close: generateItalicTag(false),
  mixable: true,
  expelEnclosingWhitespace: true,
};

const generateCodeTag = (open = true) => {
  return (_, mark) => {
    const type = /^(`|<code).*/.exec(mark.attrs.sourceMarkdown)?.[1];

    if (type === '<code') {
      return (open ? openTag : closeTag)(type.substring(1));
    }

    return '`';
  };
};

export const code = {
  open: generateCodeTag(),
  close: generateCodeTag(false),
  mixable: true,
  expelEnclosingWhitespace: true,
};

const LINK_HTML = 'linkHtml';
const LINK_MARKDOWN = 'linkMarkdown';

const linkType = (sourceMarkdown) => {
  const expression = /^(\[|<a).*/.exec(sourceMarkdown)?.[1];

  if (!expression || expression === '[') {
    return LINK_MARKDOWN;
  }

  return LINK_HTML;
};

export const link = {
  open(state, mark, parent, index) {
    if (isPlainURL(mark, parent, index, 1)) {
      return '<';
    }

    const { canonicalSrc, href, title, sourceMarkdown } = mark.attrs;

    if (linkType(sourceMarkdown) === LINK_MARKDOWN) {
      return '[';
    }

    const attrs = { href: state.esc(href || canonicalSrc) };

    if (title) {
      attrs.title = title;
    }

    return openTag('a', attrs);
  },
  close(state, mark, parent, index) {
    if (isPlainURL(mark, parent, index, -1)) {
      return '>';
    }

    const { canonicalSrc, href, title, sourceMarkdown } = mark.attrs;

    if (linkType(sourceMarkdown) === LINK_HTML) {
      return closeTag('a');
    }

    return `](${state.esc(canonicalSrc || href)}${title ? ` ${state.quote(title)}` : ''})`;
  },
};
