import Foundation

enum RedditSubmitPrefillScript {
    static func make(prefill: RedditSubmitPrefill) -> String {
        let payload: [String: Any] = [
            "body": prefill.body,
            "pollOptions": prefill.pollOptions,
            "pollDurationDays": prefill.pollDurationDays,
        ]

        guard
            let jsonData = try? JSONSerialization.data(withJSONObject: payload),
            let jsonString = String(data: jsonData, encoding: .utf8)
        else {
            return ""
        }

        return """
        (function() {
          const config = \(jsonString);

          const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));

          const queryAllDeep = (selector, root = document) => {
            const results = [];
            const visit = (node) => {
              results.push(...Array.from(node.querySelectorAll(selector)));
              Array.from(node.querySelectorAll('*')).forEach((element) => {
                if (element.shadowRoot) {
                  visit(element.shadowRoot);
                }
              });
            };
            visit(root);
            return results;
          };

          const clickPollTab = () => {
            const candidates = queryAllDeep('button, [role="tab"], [role="radio"], label, a, div[role="button"]');
            const pollControl = candidates.find((element) => {
              const text = (element.textContent || '').trim().toLowerCase();
              const label = (element.getAttribute('aria-label') || '').trim().toLowerCase();
              return text === 'poll' || label === 'poll' || label.includes('poll post');
            });
            if (!pollControl) {
              return false;
            }
            pollControl.click();
            return true;
          };

          const setFieldValue = (field, value) => {
            if (!field || value == null) {
              return;
            }
            if (field.tagName === 'TEXTAREA' || field.tagName === 'INPUT') {
              field.value = value;
            } else if (field.isContentEditable) {
              field.textContent = value;
            } else {
              return;
            }
            field.dispatchEvent(new Event('input', { bubbles: true }));
            field.dispatchEvent(new Event('change', { bubbles: true }));
          };

          const fillBody = () => {
            if (!config.body) {
              return;
            }

            const fields = queryAllDeep('textarea, div[contenteditable="true"], faceplate-textarea-input textarea, [data-testid*="body"] textarea');
            const bodyField = fields.find((field) => {
              const placeholder = (field.getAttribute('placeholder') || '').toLowerCase();
              const aria = (field.getAttribute('aria-label') || '').toLowerCase();
              return placeholder.includes('body') || placeholder.includes('text') || aria.includes('body') || aria.includes('optional');
            }) || fields[0];

            if (bodyField) {
              setFieldValue(bodyField, config.body);
            }
          };

          const pollOptionFields = () => {
            return queryAllDeep('input[type="text"], textarea').filter((field) => {
              const placeholder = (field.getAttribute('placeholder') || '').toLowerCase();
              const aria = (field.getAttribute('aria-label') || '').toLowerCase();
              const name = (field.getAttribute('name') || '').toLowerCase();
              const testId = (field.getAttribute('data-testid') || '').toLowerCase();
              return placeholder.includes('option')
                || aria.includes('option')
                || name.includes('poll')
                || testId.includes('poll-option');
            });
          };

          const clickAddOption = () => {
            const buttons = queryAllDeep('button, [role="button"]');
            const addButton = buttons.find((button) => /add.*option/i.test((button.textContent || '').trim()));
            if (addButton) {
              addButton.click();
              return true;
            }
            return false;
          };

          const fillPollOptions = async () => {
            for (let index = 0; index < config.pollOptions.length; index += 1) {
              let fields = pollOptionFields();
              let attempts = 0;

              while (fields.length <= index && attempts < 4) {
                if (!clickAddOption()) {
                  break;
                }
                await sleep(200);
                fields = pollOptionFields();
                attempts += 1;
              }

              if (fields[index]) {
                setFieldValue(fields[index], config.pollOptions[index]);
              }
            }
          };

          const selectDuration = () => {
            const label = config.pollDurationDays === 1
              ? '1 day'
              : `${config.pollDurationDays} days`;

            const controls = queryAllDeep('button, [role="radio"], label, option, span, div[role="button"]');
            const match = controls.find((control) => {
              const text = (control.textContent || '').trim().toLowerCase();
              return text === label || text.startsWith(`${config.pollDurationDays} day`);
            });

            if (match) {
              match.click();
            }
          };

          const applyPollPrefill = async () => {
            if (!clickPollTab()) {
              return false;
            }

            await sleep(500);
            fillBody();
            await fillPollOptions();
            selectDuration();
            return true;
          };

          return applyPollPrefill();
        })();
        """
    }
}