/**
 * Initialize DslEditor with CodeMirror 5
 *
 * Features:
 * - DSL-based autocompletion
 * - Line numbers
 * - Readonly support
 * - Placeholder support
 * - Textarea synchronization
 * - Debounced HTMX server update via updateCommandId
 *
 * Required CodeMirror addons:
 * - addon/hint/show-hint.js
 * - addon/hint/show-hint.css
 * - addon/display/placeholder.js
 *
 * Requires:
 * - htmx loaded globally
 *
 * @param {Object} config
 */
function initDslEditor(config) {
  const {
    elementId,
    textareaId,
    lineNumbers,
    autocompletion,
    linting,
    placeholder,
    readonly,
    updateCommandId,
    dslId,
    dsl
  } = config;

  const wrapper = document.getElementById(elementId);
  const textarea = document.getElementById(textareaId);
  const editorContainer = document.getElementById(`cm_${elementId}`);

  if (!wrapper || !textarea || !editorContainer) {
    console.error(`DslEditor: Missing elements for ${elementId}`);
    return;
  }

  if (typeof CodeMirror === "undefined") {
    console.error("DslEditor: CodeMirror 5 not loaded");
    return;
  }

  /* --------------------------------------------------
   * DSL autocompletion hint (async via server)
   * -------------------------------------------------- */

  // Characters that trigger auto-completion
  const AUTO_TRIGGER_CHARS = [".", "(", '"', " "];

  function dslHint(cm, callback) {
    const cursor = cm.getCursor();
    const text = cm.getValue();

    // Build URL with query params
    const params = new URLSearchParams({
      e_id: dslId,
      text: text,
      line: cursor.line,
      ch: cursor.ch
    });

    fetch(`/myfasthtml/completions?${params}`)
      .then(response => response.json())
      .then(data => {
        if (!data || !data.suggestions || data.suggestions.length === 0) {
          callback(null);
          return;
        }

        callback({
          list: data.suggestions.map(s => ({
            text: s.label,
            displayText: s.detail ? `${s.label} - ${s.detail}` : s.label
          })),
          from: CodeMirror.Pos(data.from.line, data.from.ch),
          to: CodeMirror.Pos(data.to.line, data.to.ch)
        });
      })
      .catch(err => {
        console.error("DslEditor: Completion error", err);
        callback(null);
      });
  }

  // Mark hint function as async for CodeMirror
  dslHint.async = true;

  /* --------------------------------------------------
   * DSL linting (async via server)
   * -------------------------------------------------- */

  function dslLint(text, updateOutput, options, cm) {
    const cursor = cm.getCursor();

    const params = new URLSearchParams({
      e_id: dslId,
      text: text,
      line: cursor.line,
      ch: cursor.ch
    });

    fetch(`/myfasthtml/validations?${params}`)
      .then(response => response.json())
      .then(data => {
        if (!data || !data.errors || data.errors.length === 0) {
          updateOutput([]);
          return;
        }

        // Convert server errors to CodeMirror lint format
        // Server returns 1-based positions, CodeMirror expects 0-based
        const annotations = data.errors.map(err => ({
          from: CodeMirror.Pos(err.line - 1, Math.max(0, err.column - 1)),
          to: CodeMirror.Pos(err.line - 1, err.column),
          message: err.message,
          severity: err.severity || "error"
        }));

        updateOutput(annotations);
      })
      .catch(err => {
        console.error("DslEditor: Linting error", err);
        updateOutput([]);
      });
  }

  // Mark lint function as async for CodeMirror
  dslLint.async = true;

  /* --------------------------------------------------
   * Register Simple Mode if available and config provided
   * -------------------------------------------------- */

  let modeName = null;

  if (typeof CodeMirror.defineSimpleMode !== "undefined" && dsl && dsl.simpleModeConfig) {
    // Generate unique mode name from DSL name
    modeName = `dsl-${dsl.name.toLowerCase().replace(/\s+/g, '-')}`;

    // Register the mode if not already registered
    if (!CodeMirror.modes[modeName]) {
      try {
        CodeMirror.defineSimpleMode(modeName, dsl.simpleModeConfig);
      } catch (err) {
        console.error(`Failed to register Simple Mode for ${dsl.name}:`, err);
        modeName = null;
      }
    }
  }

  /* --------------------------------------------------
   * Create CodeMirror editor
   * -------------------------------------------------- */

  const enableCompletion = autocompletion && dslId;
  // Only enable linting if the lint addon is loaded
  const lintAddonLoaded = typeof CodeMirror.lint !== "undefined" ||
    (CodeMirror.defaults && "lint" in CodeMirror.defaults);
  const enableLinting = linting && dslId && lintAddonLoaded;

  const editorOptions = {
    value: textarea.value || "",
    mode: modeName || undefined,  // Use Simple Mode if available
    theme: "daisy",  // Use DaisyUI theme for automatic theme switching
    lineNumbers: !!lineNumbers,
    readOnly: !!readonly,
    placeholder: placeholder || "",
    extraKeys: enableCompletion ? {
      "Ctrl-Space": "autocomplete"
    } : {},
    hintOptions: enableCompletion ? {
      hint: dslHint,
      completeSingle: false
    } : undefined
  };

  // Add linting options if enabled and addon is available
  if (enableLinting) {
    // Include linenumbers gutter if lineNumbers is enabled
    editorOptions.gutters = lineNumbers
      ? ["CodeMirror-linenumbers", "CodeMirror-lint-markers"]
      : ["CodeMirror-lint-markers"];
    editorOptions.lint = {
      getAnnotations: dslLint,
      async: true
    };
  }

  const editor = CodeMirror(editorContainer, editorOptions);

  /* --------------------------------------------------
   * Auto-trigger completion on specific characters
   * -------------------------------------------------- */

  if (enableCompletion) {
    editor.on("inputRead", function (cm, change) {
      if (change.origin !== "+input") return;

      const lastChar = change.text[change.text.length - 1];
      const lastCharOfInput = lastChar.slice(-1);

      if (AUTO_TRIGGER_CHARS.includes(lastCharOfInput)) {
        cm.showHint({completeSingle: false});
      }
    });
  }

  /* --------------------------------------------------
   * Debounced update + HTMX transport
   * -------------------------------------------------- */

  let debounceTimer = null;
  const DEBOUNCE_DELAY = 300;

  editor.on("change", function (cm) {
    const value = cm.getValue();
    textarea.value = value;

    if (!updateCommandId) return;

    clearTimeout(debounceTimer);
    debounceTimer = setTimeout(() => {
      wrapper.dispatchEvent(
        new CustomEvent("dsl-editor-update", {
          detail: {
            commandId: updateCommandId,
            value: value
          }
        })
      );
    }, DEBOUNCE_DELAY);
  });

  /* --------------------------------------------------
   * HTMX listener (LOCAL to wrapper)
   * -------------------------------------------------- */

  if (updateCommandId && typeof htmx !== "undefined") {
    wrapper.addEventListener("dsl-editor-update", function (e) {
      htmx.ajax("POST", "/myfasthtml/commands", {
        target: wrapper,
        swap: "none",
        values: {
          c_id: e.detail.commandId,
          content: e.detail.value
        }
      });
    });
  }

  /* --------------------------------------------------
   * Public API
   * -------------------------------------------------- */

  wrapper._dslEditor = {
    editor: editor,
    getContent: () => editor.getValue(),
    setContent: (content) => editor.setValue(content)
  };

  //console.debug(`DslEditor initialized: ${elementId}, DSL=${dsl?.name || "unknown"}, dsl_id=${dslId}, completion=${enableCompletion ? "enabled" : "disabled"}, linting=${enableLinting ? "enabled" : "disabled"}`);
}