(function(root, factory) {
  const api = factory();
  if (typeof module === 'object' && module.exports) module.exports = api;
  else root.issueAttachment = api;
})(typeof self !== 'undefined' ? self : this, function() {
  'use strict';

  const MAX_BYTES = 2 * 1024 * 1024;
  const IMAGE_TYPES = new Set(['image/png', 'image/jpeg', 'image/webp']);

  function namedBlob(blob, name) {
    if (typeof File === 'function') {
      return new File([blob], name, { type: blob.type });
    }
    Object.defineProperty(blob, 'name', { value: name, configurable: true });
    return blob;
  }

  async function optimizeImage(file, environment = {}) {
    if (file.size <= MAX_BYTES) return file;
    const decode = environment.createImageBitmap || globalThis.createImageBitmap;
    const makeCanvas = environment.createCanvas || (() => document.createElement('canvas'));
    if (typeof decode !== 'function') {
      throw new Error('This browser cannot optimize the screenshot. Try cropping it and choose it again.');
    }

    let bitmap;
    try {
      bitmap = await decode(file);
      const canvas = makeCanvas();
      const context = canvas && canvas.getContext && canvas.getContext('2d');
      if (!context || !bitmap.width || !bitmap.height) throw new Error('decode');
      let scale = Math.min(1, Math.sqrt(MAX_BYTES / file.size) * 0.92);
      for (let attempt = 0; attempt < 10; attempt += 1) {
        canvas.width = Math.max(1, Math.round(bitmap.width * scale));
        canvas.height = Math.max(1, Math.round(bitmap.height * scale));
        context.drawImage(bitmap, 0, 0, canvas.width, canvas.height);
        const blob = await new Promise(resolve => {
          canvas.toBlob(resolve, file.type, file.type === 'image/png' ? undefined : 0.86);
        });
        if (!blob) throw new Error('encode');
        if (blob.size > 0 && blob.size <= MAX_BYTES) return namedBlob(blob, file.name);
        scale *= 0.8;
      }
    } catch (_error) {
      throw new Error('The screenshot could not be optimized. Try cropping it and choose it again.');
    } finally {
      if (bitmap && typeof bitmap.close === 'function') bitmap.close();
    }
    throw new Error('The screenshot could not be optimized below 2 MB. Try cropping it and choose it again.');
  }

  function multipart(attachment) {
    let blob = attachment?.blob;
    if (!blob && attachment?.data) {
      const binary = atob(String(attachment.data));
      const bytes = Uint8Array.from(binary, character => character.charCodeAt(0));
      blob = new Blob([bytes], { type: String(attachment.contentType || '') });
    }
    if (!blob) throw new Error('The saved screenshot is unavailable. Retry before sending.');
    const form = new FormData();
    form.append('file', blob, String(attachment.filename || 'screenshot'));
    return form;
  }

  function create(options) {
    const upload = options.upload;
    const optimizeSelectedImage = options.optimizeImage || optimizeImage;
    const createOperationId = options.createOperationId || (() => {
      if (typeof globalThis !== 'undefined' && globalThis.crypto?.randomUUID) {
        return globalThis.crypto.randomUUID();
      }
      return Date.now().toString(36) + '-' + Math.random().toString(36).slice(2);
    });
    let selected = null;
    let confirmed = null;
    let serialized = null;
    let operationId = null;
    let selectionGeneration = 0;

    function commitSelection(file) {
      if (!file || !IMAGE_TYPES.has(file.type) || !Number.isFinite(file.size) ||
          file.size <= 0 || file.size > MAX_BYTES) {
        throw new Error('The screenshot could not be optimized below 2 MB. Try cropping it and choose it again.');
      }
      selected = file;
      confirmed = null;
      serialized = null;
      operationId = createOperationId();
      return state();
    }

    function select(file) {
      const generation = ++selectionGeneration;
      if (!file || !IMAGE_TYPES.has(file.type)) {
        throw new Error('Choose a PNG, JPEG, or WebP screenshot.');
      }
      if (!Number.isFinite(file.size) || file.size <= 0) {
        throw new Error('Choose a screenshot that is 2 MB or smaller.');
      }
      if (file.size > MAX_BYTES) {
        return Promise.resolve(optimizeSelectedImage(file)).then(optimized => {
          if (generation !== selectionGeneration) return state();
          return commitSelection(optimized);
        });
      }
      return commitSelection(file);
    }

    function clear() {
      selectionGeneration += 1;
      selected = null;
      confirmed = null;
      serialized = null;
      operationId = null;
    }

    function restore(value) {
      const contentType = String(value?.contentType || '');
      const filename = String(value?.filename || '');
      const blob = value?.blob;
      const data = String(value?.data || '');
      if (!blob && !data) {
        clear();
        throw new Error('The saved screenshot is unavailable. Retry before editing this issue.');
      }
      const padding = (data.match(/=*$/) || [''])[0].length;
      const size = blob ? Number(blob.size) : Math.max(1, Math.floor(data.length * 3 / 4) - padding);
      select({ name: filename, type: contentType, size, ...(blob ? { blob } : {}) });
      serialized = blob ? { filename, contentType, blob } : { filename, contentType, data };
      return state();
    }

    function state() {
      return selected ? {
        name: selected.name,
        size: selected.size,
        uploaded: Boolean(confirmed),
      } : null;
    }

    async function serialize() {
      if (!selected) return null;
      if (!serialized) {
        serialized = {
          filename: selected.name,
          contentType: selected.type,
          blob: selected.blob || selected,
        };
      }
      return { ...serialized };
    }

    async function prepareComment(item, body) {
      const text = String(body || '').trim();
      if (!selected) return text;
      if (!confirmed) {
        const attachment = await serialize();
        confirmed = await upload({
          repository: item.repository,
          number: item.number,
          filename: attachment.filename,
          content_type: attachment.contentType,
          ...(attachment.blob ? { blob: attachment.blob } : { data: attachment.data }),
          operation_id: operationId,
        });
        if (!confirmed || typeof confirmed.markdown !== 'string' || !confirmed.markdown) {
          confirmed = null;
          throw new Error('The server did not confirm the screenshot upload.');
        }
      }
      return text ? text + '\n\n' + confirmed.markdown : confirmed.markdown;
    }

    return { select, restore, clear, state, serialize, prepareComment };
  }

  function mount(options) {
    const controller = create(options);
    const clearSelection = controller.clear;
    let previewUrl = '';
    let selectionSequence = 0;

    function setBusy(busy) {
      options.input.disabled = Boolean(busy);
      options.remove.disabled = Boolean(busy);
    }

    function clearPreview() {
      selectionSequence += 1;
      if (previewUrl) options.revokeObjectURL(previewUrl);
      previewUrl = '';
      options.image.src = '';
      options.preview.hidden = true;
      options.input.value = '';
      options.input.disabled = false;
      clearSelection();
    }

    function showPreview(file, optimized) {
      if (previewUrl) options.revokeObjectURL(previewUrl);
      previewUrl = options.createObjectURL(file);
      options.image.src = previewUrl;
      options.meta.textContent = file.name + ' · ' + Math.ceil(file.size / 1024) + ' KB';
      options.preview.hidden = false;
      options.status.textContent = optimized ? 'Screenshot optimized and ready to upload.' :
        (options.readyMessage || 'Screenshot ready to upload with this comment.');
    }

    options.input.addEventListener('change', event => {
      const file = event.target.files && event.target.files[0];
      const sequence = ++selectionSequence;
      let result;
      try {
        result = controller.select(file);
      } catch (error) {
        options.status.textContent = error.message;
        options.input.value = '';
        return;
      }
      if (!result || typeof result.then !== 'function') {
        showPreview(file, false);
        return;
      }
      options.status.textContent = 'Optimizing screenshot…';
      options.input.disabled = true;
      return result.then(() => controller.serialize()).then(value => {
        if (sequence === selectionSequence) showPreview(value.blob, true);
      }).catch(error => {
        if (sequence === selectionSequence) {
          options.status.textContent = error.message;
          options.input.value = '';
        }
      }).finally(() => {
        if (sequence === selectionSequence) options.input.disabled = false;
      });
    });
    options.remove.addEventListener('click', () => {
      clearPreview();
      options.status.textContent = options.removedMessage || 'Screenshot removed. Your comment is unchanged.';
    });

    function restorePreview(value) {
      clearPreview();
      const restored = controller.restore(value);
      previewUrl = value.blob ? options.createObjectURL(value.blob) :
        'data:' + value.contentType + ';base64,' + value.data;
      options.image.src = previewUrl;
      options.meta.textContent = restored.name + ' · ' + Math.ceil(restored.size / 1024) + ' KB';
      options.preview.hidden = false;
      options.status.textContent = options.readyMessage || 'Screenshot ready to upload with this comment.';
      return restored;
    }

    return Object.assign(controller, { clear: clearPreview, restore: restorePreview, setBusy });
  }

  return { create, mount, multipart, optimizeImage, MAX_BYTES };
});