export const RsvInlineFormBuilder = {
  match_p(name, value) {
    return (form) => String(form[name]) === String(value);
  },
  create(datasource) {
    const fields = [];

    const builder = {
      datasource: datasource,
      fieldset(legend, width = null) {
        fields.push({ type: 'fieldset', legend, width });
        return this;
      },
      input_text(name, label, value = '') {
        fields.push({ type: 'text', name, label, value });
        return this;
      },
      input_number(name, label, value = '') {
        fields.push({ type: 'number', name, label, value });
        return this;
      },
      input_date(name, label, value = '') {
        fields.push({ type: 'date', name, label, value });
        return this;
      },
      input_time(name, label, value = '') {
        fields.push({ type: 'time', name, label, value });
        return this;
      },
      input_textarea(name, label, value = '') {
        fields.push({ type: 'textarea', name, label, value });
        return this;
      },
      input_checkbox(name, label, checked = false) {
        fields.push({ type: 'checkbox', name, label, checked });
        return this;
      },
      input_hidden(name, value) {
        fields.push({ type: 'hidden', name, value });
        return this;
      },
      input_select(name, label, options, value = '') {
        fields.push({ type: 'select', name, label, options, value });
        return this;
      },
      show_if(predicate) {
        const last = fields[fields.length - 1];
        if (last) last.show_if = predicate;
        return this;
      },
      build({ id, colspan = 1, save_label = 'Update', on_success, on_cancel } = {}) {
        const td = document.createElement('td');
        td.setAttribute('colspan', colspan);

        const form = document.createElement('form');
        const wrapper = document.createElement('div');
        wrapper.classList.add('inline-edit-wrapper');

        const hidden_inputs = [];
        let current_fieldset = null;
        let current_col = null;
        const fieldsets = [];
        const conditionals = [];

        function ensure_fieldset() {
          if (current_fieldset === null) {
            current_fieldset = document.createElement('fieldset');
            current_col = document.createElement('div');
            current_col.classList.add('inline-edit-col');
            fieldsets.push(current_fieldset);
          }
        }

        for (const field of fields) {
          if (field.type === 'hidden') {
            hidden_inputs.push(field);
            continue;
          }

          if (field.type === 'fieldset') {
            if (current_fieldset !== null) {
              current_fieldset.appendChild(current_col);
            }
            current_fieldset = document.createElement('fieldset');
            if (field.width) current_fieldset.style.width = field.width;

            const legend_el = document.createElement('legend');
            legend_el.classList.add('inline-edit-legend');
            legend_el.innerText = field.legend;
            current_fieldset.appendChild(legend_el);

            current_col = document.createElement('div');
            current_col.classList.add('inline-edit-col');
            fieldsets.push(current_fieldset);
            continue;
          }

          ensure_fieldset();

          const label_el = document.createElement('label');

          const title = document.createElement('span');
          title.classList.add('title');
          title.innerText = field.label;

          const wrap = document.createElement('span');
          wrap.classList.add('input-text-wrap');

          let input;
          if (field.type === 'select') {
            input = document.createElement('select');
            input.name = field.name;
            for (const opt of field.options) {
              const option = document.createElement('option');
              if (typeof opt === 'object' && opt !== null) {
                option.value = opt.value;
                option.textContent = opt.label;
                option.selected = String(opt.value) === String(field.value);
              } else {
                option.value = opt;
                option.textContent = opt;
                option.selected = opt === field.value;
              }
              input.appendChild(option);
            }
          } else if (field.type === 'textarea') {
            input = document.createElement('textarea');
            input.name = field.name;
            input.rows = 5;
            input.style.width = '100%';
            input.value = field.value ?? '';
          } else {
            input = document.createElement('input');
            input.type = field.type;
            input.name = field.name;
            if (field.type === 'checkbox') {
              input.checked = field.checked;
            } else {
              input.value = field.value ?? '';
            }
          }

          wrap.appendChild(input);
          label_el.replaceChildren(title, wrap);
          current_col.appendChild(label_el);

          if (field.show_if) conditionals.push({ label_el, predicate: field.show_if });
        }

        if (current_fieldset !== null) {
          current_fieldset.appendChild(current_col);
        }

        const save_row = document.createElement('div');
        save_row.classList.add('inline-edit-save', 'submit');

        const error = document.createElement('div');
        error.classList.add('notice', 'notice-error', 'notice-alt', 'inline', 'hidden');
        const error_p = document.createElement('p');
        error_p.classList.add('error');
        error.appendChild(error_p);

        const spinner = document.createElement('span');
        spinner.classList.add('spinner');

        const save_btn = document.createElement('button');
        save_btn.type = 'button';
        save_btn.classList.add('save', 'button', 'button-primary');
        save_btn.innerText = save_label;
        save_btn.onclick = () => {
          const form_data = Object.fromEntries(new FormData(form));
          for (const field of fields) {
            if (field.type === 'checkbox') {
              form_data[field.name] = field.name in form_data;
            }
          }
          spinner.classList.add('is-active');
          error.classList.add('hidden');
          builder.datasource.put(id, form_data)
            .then(() => { if (on_success) on_success(); })
            .catch(err => {
              error_p.innerText = err.message;
              error.classList.remove('hidden');
            })
            .finally(() => spinner.classList.remove('is-active'));
        };

        const cancel_btn = document.createElement('button');
        cancel_btn.type = 'button';
        cancel_btn.classList.add('cancel', 'button');
        cancel_btn.innerText = 'Cancel';
        if (on_cancel) cancel_btn.onclick = on_cancel;

        save_row.replaceChildren(save_btn, cancel_btn, spinner, error);

        for (const h of hidden_inputs) {
          const input = document.createElement('input');
          input.type = 'hidden';
          input.name = h.name;
          input.value = h.value ?? '';
          form.appendChild(input);
        }

        wrapper.replaceChildren(...fieldsets, save_row);
        form.appendChild(wrapper);
        td.appendChild(form);

        if (conditionals.length) {
          const snapshot = () => {
            const f = Object.fromEntries(new FormData(form));
            for (const field of fields) if (field.type === 'checkbox') f[field.name] = field.name in f;
            return f;
          };
          const sync_all = () => {
            const f = snapshot();
            for (const c of conditionals) c.label_el.classList.toggle('hidden', !c.predicate(f));
          };
          form.addEventListener('change', sync_all);
          form.addEventListener('input', sync_all);
          sync_all();
        }

        return td;
      },
    };

    return builder;
  },
};