import {localStorageBoolObs} from 'app/client/lib/localStorageObs';
import {docUrl, getLoginOrSignupUrl, urlState} from 'app/client/models/gristUrlState';
import {HomeModel, ViewSettings} from 'app/client/models/HomeModel';
import * as css from 'app/client/ui/DocMenuCss';
import {examples} from 'app/client/ui/ExampleInfo';
import {createDocAndOpen, importDocAndOpen} from 'app/client/ui/HomeLeftPane';
import {buildPinnedDoc} from 'app/client/ui/PinnedDocs';
import {bigBasicButton} from 'app/client/ui2018/buttons';
import {colors, mediaXSmall, testId} from 'app/client/ui2018/cssVars';
import {icon} from 'app/client/ui2018/icons';
import {cssLink} from 'app/client/ui2018/links';
import {commonUrls} from 'app/common/gristUrls';
import {Document, Workspace} from 'app/common/UserAPI';
import {dom, DomContents, DomCreateFunc, styled} from 'grainjs';

export function buildHomeIntro(homeModel: HomeModel): DomContents {
  const user = homeModel.app.currentValidUser;
  if (user) {
    return [
      css.docListHeader(`Welcome to Grist, ${user.name}!`, testId('welcome-title')),
      cssIntroSplit(
        cssIntroLeft(
          cssIntroImage({src: 'https://www.getgrist.com/themes/grist/assets/images/empty-folder.png'}),
          testId('intro-image'),
        ),
        cssIntroRight(
          cssParagraph(
            'Watch video on ',
            cssLink({href: 'https://support.getgrist.com/creating-doc/', target: '_blank'}, 'creating a document'),
            '.', dom('br'),
            'Learn more in our ', cssLink({href: commonUrls.help, target: '_blank'}, 'Help Center'), '.',
            testId('welcome-text')
          ),
          makeCreateButtons(homeModel),
        ),
      ),
    ];
  } else {
    return [
      cssIntroSplit(
        cssIntroLeft(
          cssLink({href: 'https://support.getgrist.com/creating-doc/', target: '_blank'},
            cssIntroImage({src: 'https://www.getgrist.com/themes/grist/assets/images/video-create-doc.png'}),
          ),
          testId('intro-image'),
        ),
        cssIntroRight(
          css.docListHeader('Welcome to Grist!', testId('welcome-title')),
          cssParagraph(
            'You can explore and experiment without logging in. ',
            'To save your work, however, you’ll need to ',
            cssLink({href: getLoginOrSignupUrl()}, 'sign up'), '.', dom('br'),
            'Learn more in our ', cssLink({href: commonUrls.help, target: '_blank'}, 'Help Center'), '.',
            testId('welcome-text')
          ),
          makeCreateButtons(homeModel),
        ),
      ),
    ];
  }
}

function makeCreateButtons(homeModel: HomeModel) {
  return cssBtnGroup(
    cssBtn(cssBtnIcon('Import'), 'Import Document', testId('intro-import-doc'),
      dom.on('click', () => importDocAndOpen(homeModel)),
    ),
    cssBtn(cssBtnIcon('Page'), 'Create Empty Document', testId('intro-create-doc'),
      dom.on('click', () => createDocAndOpen(homeModel)),
    ),
  );
}

export function buildExampleList(home: HomeModel, workspace: Workspace, viewSettings: ViewSettings) {
  const hideExamplesObs = localStorageBoolObs('hide-examples');
  return cssDocBlock(
    dom.autoDispose(hideExamplesObs),
    cssDocBlockHeader(css.docBlockHeaderLink.cls(''), css.docHeaderIcon('FieldTable'), 'Examples & Templates',
      dom.domComputed(hideExamplesObs, (collapsed) =>
        collapsed ? cssCollapseIcon('Expand') : cssCollapseIcon('Collapse')
      ),
      dom.on('click', () => hideExamplesObs.set(!hideExamplesObs.get())),
      testId('examples-header'),
    ),
    dom.maybe((use) => !use(hideExamplesObs), () => _buildExampleListDocs(home, workspace, viewSettings)),
    css.docBlock.cls((use) => '-' + use(home.currentView)),
    testId('examples-list'),
  );
}

export function buildExampleListBody(home: HomeModel, workspace: Workspace, viewSettings: ViewSettings) {
  return cssDocBlock(
    _buildExampleListDocs(home, workspace, viewSettings),
    css.docBlock.cls((use) => '-' + use(viewSettings.currentView)),
    testId('examples-body'),
  );
}

function _buildExampleListDocs(home: HomeModel, workspace: Workspace, viewSettings: ViewSettings) {
  return [
    cssParagraph(
      'Explore these examples, read tutorials based on them, or use any of them as a template.',
      testId('examples-desc'),
    ),
    dom.domComputed(viewSettings.currentView, (view) =>
      dom.forEach(workspace.docs, doc => buildExampleItem(doc, home, view))
    ),
  ];
}

function buildExampleItem(doc: Document, home: HomeModel, view: 'list'|'icons') {
  const ex = examples.find((e) => e.matcher.test(doc.name));
  if (view === 'icons') {
    return buildPinnedDoc(home, doc, ex);
  } else {
    return css.docRowWrapper(
      cssDocRowLink(
        urlState().setLinkUrl(docUrl(doc)),
        cssDocName(ex?.title || doc.name, testId('examples-doc-name')),
        ex ? cssItemDetails(ex.desc, testId('examples-desc')) : null,
      ),
      testId('examples-doc'),
    );
  }
}

const cssIntroSplit = styled(css.docBlock, `
  display: flex;
  align-items: center;

  @media ${mediaXSmall} {
    & {
      display: block;
    }
  }
`);

const cssIntroLeft = styled('div', `
  flex: 0.4 1 0px;
  overflow: hidden;
  max-height: 150px;
  text-align: center;
  margin: 32px 0;
`);

const cssIntroRight = styled('div', `
  flex: 0.6 1 0px;
  overflow: auto;
  margin-left: 8px;
`);

const cssParagraph = styled(css.docBlock, `
  line-height: 1.6;
`);

const cssBtnGroup = styled('div', `
  display: inline-flex;
  flex-direction: column;
  align-items: stretch;
  margin-top: -16px;
`);

const cssBtn = styled(bigBasicButton, `
  display: block;
  margin-right: 16px;
  margin-top: 16px;
  text-align: left;
`);

const cssBtnIcon = styled(icon, `
  margin-right: 8px;
`);

const cssDocRowLink = styled(css.docRowLink, `
  display: block;
  height: unset;
  line-height: 1.6;
  padding: 8px 0;
`);

const cssDocName = styled(css.docName, `
  margin: 0 16px;
`);

const cssItemDetails = styled('div', `
  margin: 0 16px;
  line-height: 1.6;
  color: ${colors.slate};
`);

const cssDocBlock = styled(css.docBlock, `
  margin-top: 32px;
`);

const cssDocBlockHeader = styled('div', `
  cursor: pointer;
`);

const cssCollapseIcon = styled(css.docHeaderIcon, `
  margin-left: 8px;
`);


// Helper to create an image scaled down to half of its intrinsic size.
// Based on https://stackoverflow.com/a/25026615/328565
const cssIntroImage: DomCreateFunc<HTMLDivElement> =
  (...args) => _cssImageWrap1(_cssImageWrap2(_cssImageScaled(...args)));

const _cssImageWrap1 = styled('div', `width: 200%; margin-left: -50%;`);
const _cssImageWrap2 = styled('div', `display: inline-block;`);
const _cssImageScaled = styled('img', `width: 50%;`);