import { ElementTypeEnum } from '../constants';
import {
  createElement,
  getElementByRole,
  getViewBox,
  setAttributes,
  setElementRole,
  traverse,
} from '../utils';
import { embedFonts } from './font';
import type { SVGExportOptions } from './types';

const VIEWBOX_CHANGE_TOLERANCE = 0.5;

export async function exportToSVGString(
  svg: SVGSVGElement,
  options: Omit<SVGExportOptions, 'type'> = {},
) {
  const node = await exportToSVG(svg, options);
  const str = new XMLSerializer().serializeToString(node);
  return 'data:image/svg+xml;charset=utf-8,' + encodeURIComponent(str);
}

function getExportViewBox(svg: SVGSVGElement) {
  if (svg.hasAttribute('viewBox')) return getViewBox(svg);

  const width = parseAbsoluteLength(svg.getAttribute('width'));
  const height = parseAbsoluteLength(svg.getAttribute('height'));
  if (
    !Number.isNaN(width) &&
    width > 0 &&
    !Number.isNaN(height) &&
    height > 0
  ) {
    return { x: 0, y: 0, width, height };
  }

  const rect = svg.getBoundingClientRect();
  if (rect.width > 0 && rect.height > 0) {
    return { x: 0, y: 0, width: rect.width, height: rect.height };
  }

  return null;
}

function parseAbsoluteLength(value: string | null): number {
  if (!value) return Number.NaN;
  const trimmed = value.trim();
  if (!trimmed) return Number.NaN;
  if (!/^[-+]?(?:\d+\.?\d*|\.\d+)(?:px)?$/.test(trimmed)) return Number.NaN;
  return Number.parseFloat(trimmed);
}

function measureSpanContentHeight(span: HTMLElement): number {
  const prevHeight = span.style.height;
  const prevOverflow = span.style.overflow;
  try {
    span.style.height = 'max-content';
    span.style.overflow = 'hidden';
    void span.offsetHeight; // force reflow
    return span.scrollHeight;
  } finally {
    span.style.height = prevHeight;
    span.style.overflow = prevOverflow;
  }
}

function measureSpanContentWidth(span: HTMLElement): number {
  const prevWidth = span.style.width;
  const prevOverflow = span.style.overflow;
  try {
    span.style.width = 'max-content';
    span.style.overflow = 'hidden';
    void span.offsetWidth; // force reflow
    return span.scrollWidth;
  } finally {
    span.style.width = prevWidth;
    span.style.overflow = prevOverflow;
  }
}

// Returns [left, top, right, bottom] in SVG coordinates for a foreignObject,
// accounting for flex alignment: bottom/center-aligned content can overflow,
// and horizontally aligned content can overflow as well.
function getFOContentBoundsInSVG(
  fo: SVGForeignObjectElement,
  content: HTMLElement,
  toSVGCoord: (x: number, y: number) => SVGPoint,
): [number, number, number, number] {
  const foRect = fo.getBoundingClientRect();
  const foTopLeft = toSVGCoord(foRect.left, foRect.top);
  const foBottomRight = toSVGCoord(foRect.right, foRect.bottom);

  const foLeftSVG = foTopLeft.x;
  const foTopSVG = foTopLeft.y;
  const foRightSVG = foBottomRight.x;
  const foBottomSVG = foBottomRight.y;

  const foWidthSVG = foRightSVG - foLeftSVG;
  const foHeightSVG = foBottomSVG - foTopSVG;

  const svgUnitsPerClientPxY =
    foRect.height > 0 ? foHeightSVG / foRect.height : 1;
  const svgUnitsPerClientPxX = foRect.width > 0 ? foWidthSVG / foRect.width : 1;

  // Measure actual content dimensions
  const realScrollHeight = measureSpanContentHeight(content);
  const contentHeightSVG =
    realScrollHeight > 0
      ? realScrollHeight * svgUnitsPerClientPxY
      : foHeightSVG;

  const realScrollWidth = measureSpanContentWidth(content);
  const contentWidthSVG =
    realScrollWidth > 0 ? realScrollWidth * svgUnitsPerClientPxX : foWidthSVG;

  const computedStyle = window.getComputedStyle(content);
  const alignItems = computedStyle.alignItems;
  const justifyContent = computedStyle.justifyContent;

  // Calculate vertical bounds
  let top: number, bottom: number;
  if (alignItems === 'flex-end' || alignItems === 'end') {
    top = foBottomSVG - contentHeightSVG;
    bottom = foBottomSVG;
  } else if (alignItems === 'center') {
    const overflowY = contentHeightSVG - foHeightSVG;
    top = foTopSVG - overflowY / 2;
    bottom = foBottomSVG + overflowY / 2;
  } else {
    top = foTopSVG;
    bottom = foTopSVG + contentHeightSVG;
  }

  // Calculate horizontal bounds
  let left: number, right: number;
  if (
    justifyContent === 'flex-end' ||
    justifyContent === 'end' ||
    justifyContent === 'right'
  ) {
    left = foRightSVG - contentWidthSVG;
    right = foRightSVG;
  } else if (justifyContent === 'center') {
    const overflowX = contentWidthSVG - foWidthSVG;
    left = foLeftSVG - overflowX / 2;
    right = foRightSVG + overflowX / 2;
  } else {
    left = foLeftSVG;
    right = foLeftSVG + contentWidthSVG;
  }

  return [left, top, right, bottom];
}

/**
 * Computes a viewBox that fully covers all foreignObject text content,
 * accounting for overflow caused by flex alignment (bottom/center align
 * can push content outside the foreignObject bounds).
 */
function computeFullViewBox(svg: SVGSVGElement): string | null {
  const viewBox = getExportViewBox(svg);
  if (!viewBox) return null;

  if (typeof svg.getScreenCTM !== 'function') return null;
  const screenCTM = svg.getScreenCTM();
  if (!screenCTM) return null;
  const inverseCTM = screenCTM.inverse();

  const toSVGCoord = (clientX: number, clientY: number) => {
    const pt = svg.createSVGPoint();
    pt.x = clientX;
    pt.y = clientY;
    return pt.matrixTransform(inverseCTM);
  };

  let minX = viewBox.x;
  let minY = viewBox.y;
  let maxX = viewBox.x + viewBox.width;
  let maxY = viewBox.y + viewBox.height;

  svg
    .querySelectorAll<SVGForeignObjectElement>('foreignObject')
    .forEach((fo) => {
      const content = fo.firstElementChild as HTMLElement;
      if (!content) return;
      const [left, top, right, bottom] = getFOContentBoundsInSVG(
        fo,
        content,
        toSVGCoord,
      );
      minX = Math.min(minX, left);
      minY = Math.min(minY, top);
      maxX = Math.max(maxX, right);
      maxY = Math.max(maxY, bottom);
    });

  const newX = minX;
  const newY = minY;
  const newWidth = maxX - newX;
  const newHeight = maxY - newY;
  if (
    newWidth <= viewBox.width + VIEWBOX_CHANGE_TOLERANCE &&
    newHeight <= viewBox.height + VIEWBOX_CHANGE_TOLERANCE &&
    newX >= viewBox.x - VIEWBOX_CHANGE_TOLERANCE &&
    newY >= viewBox.y - VIEWBOX_CHANGE_TOLERANCE
  )
    return null;

  return `${newX} ${newY} ${newWidth} ${newHeight}`;
}

export async function exportToSVG(
  svg: SVGSVGElement,
  options: Omit<SVGExportOptions, 'type'> = {},
) {
  const {
    removeBackground = false,
    embedResources = true,
    removeIds = false,
  } = options;
  const clonedSVG = svg.cloneNode(true) as SVGSVGElement;

  if (typeof document !== 'undefined') {
    const fullViewBox = computeFullViewBox(svg);
    if (fullViewBox) {
      clonedSVG.setAttribute('viewBox', fullViewBox);
    }
  }

  const { width, height } = getViewBox(clonedSVG);
  setAttributes(clonedSVG, { width, height });

  if (removeIds) {
    inlineUseElements(clonedSVG);
    inlineDefsReferences(clonedSVG);
  } else {
    await embedIcons(clonedSVG);
  }
  await embedFonts(clonedSVG, embedResources);

  if (removeBackground) {
    removeSVGBackground(clonedSVG);
  }
  cleanSVG(clonedSVG);

  return clonedSVG;
}

async function embedIcons(svg: SVGSVGElement) {
  const icons = svg.querySelectorAll('use');
  const defs = getDefs(svg);

  icons.forEach((icon) => {
    const href = icon.getAttribute('href');
    if (!href) return;
    const existsSymbol = svg.querySelector(href);

    if (!existsSymbol) {
      const symbolElement = document.querySelector(href);
      if (symbolElement) {
        defs.appendChild(symbolElement.cloneNode(true));
      }
    }
  });
}

const iconRole = 'icon-defs';
function getDefs(svg: SVGSVGElement) {
  const defs = getElementByRole(svg, iconRole);
  if (defs) return defs;
  const _defs = createElement('defs');
  setElementRole(_defs, iconRole);
  svg.prepend(_defs);
  return _defs;
}

function inlineUseElements(svg: SVGSVGElement) {
  const uses = Array.from(svg.querySelectorAll<SVGUseElement>('use'));
  if (!uses.length) return;

  uses.forEach((use) => {
    const href = getUseHref(use);
    if (!href || !href.startsWith('#')) return;
    const target = resolveUseTarget(svg, href);
    if (!target || target === use) return;

    const replacement = createInlineElement(use, target);
    if (!replacement) return;
    use.replaceWith(replacement);
  });
}

function getUseHref(use: SVGUseElement) {
  return use.getAttribute('href') ?? use.getAttribute('xlink:href');
}

function resolveUseTarget(svg: SVGSVGElement, href: string) {
  const localTarget = svg.querySelector(href);
  if (localTarget) return localTarget as SVGElement;
  const docTarget = document.querySelector(href);
  return docTarget as SVGElement | null;
}

function createInlineElement(use: SVGUseElement, target: SVGElement) {
  const tag = target.tagName.toLowerCase();
  if (tag === 'symbol') {
    return materializeSymbol(use, target as SVGSymbolElement);
  }
  if (tag === 'svg') {
    return materializeSVG(use, target as SVGSVGElement);
  }
  return materializeElement(use, target);
}

function materializeSymbol(use: SVGUseElement, symbol: SVGSymbolElement) {
  const symbolClone = symbol.cloneNode(true) as SVGSymbolElement;
  const svg = createElement<SVGSVGElement>('svg');

  applyAttributes(svg, symbolClone, new Set(['id']));
  applyAttributes(svg, use, new Set(['href', 'xlink:href']));

  while (symbolClone.firstChild) {
    svg.appendChild(symbolClone.firstChild);
  }

  return svg;
}

function materializeSVG(use: SVGUseElement, source: SVGSVGElement) {
  const clone = source.cloneNode(true) as SVGSVGElement;
  clone.removeAttribute('id');
  applyAttributes(clone, use, new Set(['href', 'xlink:href']));
  return clone;
}

function materializeElement(use: SVGUseElement, source: SVGElement) {
  const clone = source.cloneNode(true) as SVGElement;
  clone.removeAttribute('id');

  const wrapper = createElement<SVGGElement>('g');
  applyAttributes(
    wrapper,
    use,
    new Set(['href', 'xlink:href', 'x', 'y', 'width', 'height', 'transform']),
  );

  const transform = buildUseTransform(use);
  if (transform) {
    wrapper.setAttribute('transform', transform);
  }

  wrapper.appendChild(clone);
  return wrapper;
}

function buildUseTransform(use: SVGUseElement) {
  const x = use.getAttribute('x');
  const y = use.getAttribute('y');
  const translate = x || y ? `translate(${x ?? 0} ${y ?? 0})` : '';
  const transform = use.getAttribute('transform') ?? '';
  if (translate && transform) return `${translate} ${transform}`;
  return translate || transform || null;
}

function applyAttributes(
  target: SVGElement,
  source: SVGElement,
  exclude: Set<string> = new Set(),
) {
  Array.from(source.attributes).forEach((attr) => {
    if (exclude.has(attr.name)) return;
    if (attr.name === 'style') {
      mergeStyleAttribute(target, attr.value);
      return;
    }
    if (attr.name === 'class') {
      mergeClassAttribute(target, attr.value);
      return;
    }
    target.setAttribute(attr.name, attr.value);
  });
}

function mergeStyleAttribute(target: SVGElement, value: string) {
  const current = target.getAttribute('style');
  if (!current) {
    target.setAttribute('style', value);
    return;
  }
  const separator = current.trim().endsWith(';') ? '' : ';';
  target.setAttribute('style', `${current}${separator}${value}`);
}

function mergeClassAttribute(target: SVGElement, value: string) {
  const current = target.getAttribute('class');
  if (!current) {
    target.setAttribute('class', value);
    return;
  }
  target.setAttribute('class', `${current} ${value}`.trim());
}

const urlRefRegex = /url\(\s*['"]?#([^'")\s]+)['"]?\s*\)/g;
function inlineDefsReferences(svg: SVGSVGElement) {
  const referencedIds = collectReferencedIds(svg);
  if (referencedIds.size === 0) {
    removeDefs(svg);
    return;
  }

  const defsDataUrl = createDefsDataUrl(svg, referencedIds);
  if (!defsDataUrl) return;

  traverse(svg, (node) => {
    if (node.tagName.toLowerCase() === 'defs') return false;
    const attrs = Array.from(node.attributes);
    attrs.forEach((attr) => {
      const value = attr.value;
      if (!value.includes('url(')) return;
      const updated = value.replace(urlRefRegex, (_match, id) => {
        const encodedId = encodeURIComponent(id);
        return `url("${defsDataUrl}#${encodedId}")`;
      });
      if (updated !== value) node.setAttribute(attr.name, updated);
    });
  });

  removeDefs(svg);
}

function collectReferencedIds(svg: SVGSVGElement) {
  const ids = new Set<string>();
  traverse(svg, (node) => {
    if (node.tagName.toLowerCase() === 'defs') return false;
    collectIdsFromAttributes(node, (id) => ids.add(id));
  });
  return ids;
}

function collectIdsFromAttributes(
  node: SVGElement,
  addId: (id: string) => void,
) {
  for (const attr of Array.from(node.attributes)) {
    const value = attr.value;
    if (value.includes('url(')) {
      for (const match of value.matchAll(urlRefRegex)) {
        if (match[1]) addId(match[1]);
      }
    }
    if (
      (attr.name === 'href' || attr.name === 'xlink:href') &&
      value[0] === '#'
    ) {
      addId(value.slice(1));
    }
  }
}

function createDefsDataUrl(svg: SVGSVGElement, ids: Set<string>) {
  if (ids.size === 0) return null;

  const collected = collectDefElements(svg, ids);
  if (collected.size === 0) return null;

  const defsSvg = createElement<SVGSVGElement>('svg', {
    xmlns: 'http://www.w3.org/2000/svg',
    'xmlns:xlink': 'http://www.w3.org/1999/xlink',
  });
  const defs = createElement<SVGDefsElement>('defs');

  collected.forEach((node) => {
    defs.appendChild(node.cloneNode(true));
  });

  if (!defs.children.length) return null;
  defsSvg.appendChild(defs);

  const serialized = new XMLSerializer().serializeToString(defsSvg);
  return 'data:image/svg+xml;charset=utf-8,' + encodeURIComponent(serialized);
}

function collectDefElements(svg: SVGSVGElement, ids: Set<string>) {
  const collected = new Map<string, SVGElement>();
  const queue = Array.from(ids);
  const queued = new Set(queue);
  const visited = new Set<string>();
  const enqueue = (id: string) => {
    if (visited.has(id) || queued.has(id)) return;
    queue.push(id);
    queued.add(id);
  };

  while (queue.length) {
    const id = queue.shift()!;
    if (!id) continue;
    if (visited.has(id)) continue;
    visited.add(id);

    const selector = `#${escapeCssId(id)}`;
    const target = svg.querySelector(selector);
    if (!target) continue;
    collected.set(id, target as SVGElement);

    traverse(target as SVGElement, (node) => {
      collectIdsFromAttributes(node, enqueue);
    });
  }

  return collected;
}

// Fallback implementation based on the CSS.escape algorithm
function cssEscape(value: string): string {
  const string = String(value);
  const length = string.length;
  let result = '';

  if (length === 0) {
    return '';
  }

  for (let i = 0; i < length; i++) {
    const codeUnit = string.charCodeAt(i);

    // Null character
    if (codeUnit === 0x0000) {
      result += '\uFFFD';
      continue;
    }

    // Control characters or DEL
    if ((codeUnit >= 0x0001 && codeUnit <= 0x001f) || codeUnit === 0x007f) {
      result += '\\' + codeUnit.toString(16) + ' ';
      continue;
    }

    // Escape if first character is a digit
    if (i === 0 && codeUnit >= 0x0030 && codeUnit <= 0x0039) {
      result += '\\' + codeUnit.toString(16) + ' ';
      continue;
    }

    // Escape if second character is a digit and first is a hyphen
    if (
      i === 1 &&
      codeUnit >= 0x0030 &&
      codeUnit <= 0x0039 &&
      string.charCodeAt(0) === 0x002d
    ) {
      result += '\\' + codeUnit.toString(16) + ' ';
      continue;
    }

    // If the character is the first and is a hyphen followed by end of string, escape it
    if (i === 0 && length === 1 && codeUnit === 0x002d) {
      result += '\\' + string.charAt(i);
      continue;
    }

    // Characters that are safe to use unescaped
    if (
      codeUnit >= 0x0080 ||
      (codeUnit >= 0x0030 && codeUnit <= 0x0039) || // 0-9
      (codeUnit >= 0x0041 && codeUnit <= 0x005a) || // A-Z
      (codeUnit >= 0x0061 && codeUnit <= 0x007a) || // a-z
      codeUnit === 0x002d || // -
      codeUnit === 0x005f // _
    ) {
      result += string.charAt(i);
      continue;
    }

    // All other characters
    result += '\\' + string.charAt(i);
  }

  return result;
}

function escapeCssId(id: string) {
  if (globalThis.CSS && typeof globalThis.CSS.escape === 'function') {
    return globalThis.CSS.escape(id);
  }

  return cssEscape(id);
}

function removeDefs(svg: SVGSVGElement) {
  const defsList = Array.from(svg.querySelectorAll('defs'));
  defsList.forEach((defs) => defs.remove());
}

function cleanSVG(svg: SVGSVGElement) {
  removeBtnGroup(svg);
  removeTransientContainer(svg);
  removeUselessAttrs(svg);

  clearDataset(svg);
}

function removeSVGBackground(svg: SVGSVGElement) {
  svg.style.removeProperty('background-color');
  const background = getElementByRole(svg, ElementTypeEnum.Background);
  background?.remove();
}

function removeBtnGroup(svg: SVGSVGElement) {
  const btnGroup = getElementByRole(svg, ElementTypeEnum.BtnsGroup);
  btnGroup?.remove();

  const btnIconDefs = getElementByRole(svg, 'btn-icon-defs');
  btnIconDefs?.remove();
}

function removeTransientContainer(svg: SVGSVGElement) {
  const transientContainer = svg.querySelector(
    '[data-element-type=transient-container]',
  );
  transientContainer?.remove();
}

function removeUselessAttrs(svg: SVGSVGElement) {
  const groups = svg.querySelectorAll('g');
  groups.forEach((group) => {
    group.removeAttribute('x');
    group.removeAttribute('y');
    group.removeAttribute('width');
    group.removeAttribute('height');
  });
}

function clearDataset(svg: SVGSVGElement) {
  traverse(svg, (node) => {
    for (const key in node.dataset) {
      delete node.dataset[key];
    }
  });
}