refactor: extract render entrypoint & add cropRender function

tests/checkBoardRender.ts

@@ -0,0 +1,93 @@
+import { getCharacterWidth } from "../src/logic/character";
+import type { BoardRender } from "../src/types/render";
+
+function isValidColor(color: string): boolean {
+  return /^[0-9A-F]$/.test(color);
+}
+
+interface Options {
+  /**
+   * Whether to allow the width of a character to be narrower than the "correct" width.
+   *
+   * For partial renders, some wide characters may be clipped to a narrower width. This option allows for that.
+   */
+  allowsNarrowerWidth?: boolean;
+}
+
+export function checkBoardRender(render: BoardRender, options?: Options) {
+  let chLine = "";
+  let colorLine = "";
+  let bgColorLine = "";
+  let widthLine = "";
+  let lines = 0;
+  const ch = [...render.ch];
+  const chLength = ch.length;
+
+  let unsafeCurrentOffset = 0;
+
+  function isCorrectWidth(cWd: number, cCh: string): boolean {
+    const correctWidth = getCharacterWidth(cCh);
+    return options?.allowsNarrowerWidth
+      ? cWd <= correctWidth && cWd > 0
+      : cWd === correctWidth;
+  }
+
+  for (let i = 0; i < chLength; i++) {
+    const cCh = ch[i];
+    const cCo = render.color[i];
+    const cBg = render.bg_color[i];
+    const cWd = render.width[i];
+
+    const printSituation = () => {
+      console.error(
+        "offset:",
+        i,
+        "offset (unsafe):",
+        unsafeCurrentOffset,
+        "cCh:",
+        JSON.stringify(cCh),
+        "cCo:",
+        JSON.stringify(cCo),
+        "cBg:",
+        JSON.stringify(cBg),
+        "cWd:",
+        JSON.stringify(cWd),
+      );
+      console.error("ch:      ", chLine);
+      console.error("color:   ", colorLine);
+      console.error("bg_color:", bgColorLine);
+      console.error("width:   ", widthLine);
+    };
+
+    if (typeof cCh !== "string") {
+      printSituation();
+      throw new Error("cCh is not string");
+    }
+
+    if (!isValidColor(cCo) || !isValidColor(cBg)) {
+      printSituation();
+      throw new Error("cCo or cBg is not valid");
+    }
+
+    if (!isCorrectWidth(cWd, cCh)) {
+      printSituation();
+      throw new Error("cWd is wrong");
+    }
+
+    chLine += cCh;
+    colorLine += cCo.padEnd(cWd);
+    bgColorLine += cBg.padEnd(cWd);
+    widthLine += String(cWd).padEnd(cWd);
+    unsafeCurrentOffset += cCh.length;
+
+    if (colorLine.length === render.w) {
+      lines++;
+      chLine = "";
+      colorLine = "";
+      bgColorLine = "";
+      widthLine = "";
+    }
+  }
+
+  if (lines !== render.h) throw new Error("board height error");
+}