import type { EditorState, Range } from "@codemirror/state";
import { syntaxTree } from "@codemirror/language";
import { Decoration } from "@codemirror/view";
import {
  decoratorStateField,
  invisibleDecoration,
  isCursorInRange,
} from "./util.ts";
import type { Client } from "../client.ts";
import { parse as parseLua } from "../space_lua/parse.ts";
import type { LuaBlock, LuaFunctionCallStatement } from "../space_lua/ast.ts";
import { evalExpression } from "../space_lua/eval.ts";
import {
  LuaEnv,
  LuaRuntimeError,
  LuaStackFrame,
  LuaTable,
  luaValueToJS,
  singleResult,
} from "../space_lua/runtime.ts";
import { isTaggedFloat } from "../space_lua/numeric.ts";
import {
  encodeRef,
  getNameFromPath,
} from "@silverbulletmd/silverbullet/lib/ref";
import { resolveASTReference } from "../space_lua.ts";
import { LuaWidget } from "./lua_widget.ts";

export function luaDirectivePlugin(client: Client) {
  return decoratorStateField((state: EditorState) => {
    const widgets: Range<Decoration>[] = [];

    let shouldRender = true;

    // Don't render Lua directives of federated pages (security)
    if (!client.clientSystem.scriptsLoaded) {
      return Decoration.none;
    }

    syntaxTree(state).iterate({
      enter: (node) => {
        // Disable rendering of Lua directives in #meta/template pages
        // Either in frontmatter
        if (node.name === "FrontMatterCode") {
          const text = state.sliceDoc(node.from, node.to);
          try {
            // Very ad-hoc regex to detect if meta/template appears in the tag list
            if (/tags:.*meta\/template/s.exec(text)) {
              shouldRender = false;
              return;
            }
          } catch {
            // Ignore
          }
        }
        // Or with a hash tag
        if (node.name === "Hashtag") {
          const text = state.sliceDoc(node.from, node.to);
          if (text.startsWith("#meta/template")) {
            shouldRender = false;
            return;
          }
        }

        if (node.name !== "LuaDirective") {
          return;
        }

        if (isCursorInRange(state, [node.from, node.to])) {
          return;
        }

        const codeText = state.sliceDoc(node.from, node.to);
        const expressionText = codeText.slice(2, -1);
        const currentPageMeta = client.currentPageMeta();
        widgets.push(
          Decoration.widget({
            widget: new LuaWidget(
              client,
              `lua:${expressionText}:${currentPageMeta?.name}`,
              expressionText,
              codeText,
              async (bodyText) => {
                if (bodyText.trim().length === 0) {
                  return "**Error:** Empty Lua expression";
                }
                try {
                  const parsedLua = parseLua(`_(${bodyText})`) as LuaBlock;
                  const expr = (
                    parsedLua.statements[0] as LuaFunctionCallStatement
                  ).call.args[0];

                  const tl = new LuaEnv();
                  tl.setLocal(
                    "currentPage",
                    currentPageMeta ||
                      (client.ui.viewState.current
                        ? {
                            name: getNameFromPath(
                              client.ui.viewState.current.path,
                            ),
                          }
                        : undefined),
                  );
                  const sf = LuaStackFrame.createWithGlobalEnv(
                    client.clientSystem.spaceLuaEnv.env,
                    expr.ctx,
                  );
                  const threadLocalizedEnv = new LuaEnv(
                    client.clientSystem.spaceLuaEnv.env,
                  );
                  threadLocalizedEnv.setLocal("_CTX", tl);
                  const rawResult = singleResult(
                    await evalExpression(expr, threadLocalizedEnv, sf),
                  );
                  // keep tagged floats as-is for proper formatting
                  if (
                    isTaggedFloat(rawResult) ||
                    typeof rawResult === "number"
                  ) {
                    return rawResult;
                  }
                  if (rawResult instanceof LuaTable) {
                    if (rawResult.rawGet("_isWidget")) {
                      return luaValueToJS(rawResult, sf);
                    }
                    return rawResult;
                  }
                  // everything else needs luaValueToJS for widget support
                  return luaValueToJS(rawResult, sf);
                } catch (e: any) {
                  if (e instanceof LuaRuntimeError) {
                    if (e.sf?.astCtx) {
                      const source = resolveASTReference(e.sf.astCtx);
                      if (source) {
                        // We know the origin node of the error, let's reference it
                        return `**Lua error:** ${e.message} (Origin: [[${encodeRef(
                          source,
                        )}]])`;
                      }
                    }
                  }
                  return `**Lua error:** ${e.message}`;
                }
              },
              true,
              true,
              null,
            ),
          }).range(node.to),
        );

        if (!client.ui.viewState.uiOptions.markdownSyntaxRendering) {
          widgets.push(invisibleDecoration.range(node.from, node.to));
        }
      },
    });

    if (!shouldRender) {
      return Decoration.set([]);
    }

    return Decoration.set(widgets, true);
  });
}