feat : add image gen

lib/overview-image.ts

@@ -0,0 +1,75 @@
+export const overviewRoles = ["Main DPS", "Sub DPS", "Support"] as const;
+
+export type OverviewRole = (typeof overviewRoles)[number];
+
+export const elementOrder = [
+  "Pyro",
+  "Hydro",
+  "Anemo",
+  "Electro",
+  "Dendro",
+  "Cryo",
+  "Geo",
+] as const;
+
+const weaponIconNames: Record<string, string> = {
+  WEAPON_SWORD_ONE_HAND: "sword.png",
+  WEAPON_CLAYMORE: "claymore.png",
+  WEAPON_POLE: "polearm.png",
+  WEAPON_BOW: "bow.png",
+  WEAPON_CATALYST: "catalyst.png",
+};
+
+export function normalizeHex(value: string): string | null {
+  const trimmed = value.trim();
+  if (!/^#[\da-f]{6}$/iu.test(trimmed)) return null;
+  return trimmed.toUpperCase();
+}
+
+function mixHex(hex: string, target: number, amount: number): string {
+  const normalized = normalizeHex(hex);
+  if (!normalized) return hex;
+  const channels = [1, 3, 5].map((offset) =>
+    Number.parseInt(normalized.slice(offset, offset + 2), 16),
+  );
+  return `#${channels
+    .map((channel) =>
+      Math.round(channel + (target - channel) * amount)
+        .toString(16)
+        .padStart(2, "0"),
+    )
+    .join("")}`.toUpperCase();
+}
+
+function mixColors(left: string, right: string): string {
+  const leftHex = normalizeHex(left) ?? "#E9A51A";
+  const rightHex = normalizeHex(right) ?? leftHex;
+  const channels = [1, 3, 5].map((offset) =>
+    Math.round(
+      (Number.parseInt(leftHex.slice(offset, offset + 2), 16) +
+        Number.parseInt(rightHex.slice(offset, offset + 2), 16)) /
+        2,
+    ),
+  );
+  return `#${channels.map((channel) => channel.toString(16).padStart(2, "0")).join("")}`.toUpperCase();
+}
+
+export function accentGradient(start: string, end = start): string {
+  const normalizedStart = normalizeHex(start) ?? "#E9A51A";
+  const normalizedEnd = normalizeHex(end) ?? normalizedStart;
+  const startEdge = mixHex(normalizedStart, 0, 0.12);
+  const endEdge = mixHex(normalizedEnd, 0, 0.12);
+  const highlight = mixHex(mixColors(normalizedStart, normalizedEnd), 255, 0.35);
+  return `linear-gradient(90deg, ${startEdge} 0%, ${normalizedStart} 25%, ${highlight} 50%, ${normalizedEnd} 75%, ${endEdge} 100%)`;
+}
+
+export function weaponTypeIconPath(weaponType: string | null): string | null {
+  const fileName = weaponType ? weaponIconNames[weaponType] : undefined;
+  return fileName ? `/icon/weapon-types/${fileName}` : null;
+}
+
+export function overviewFileName(characterKey: string, role: OverviewRole): string {
+  const safeKey = characterKey.replace(/[^\p{L}\p{N}._-]+/gu, "-");
+  const safeRole = role.toLowerCase().replaceAll(" ", "-");
+  return `overview-${safeKey}-${safeRole}.png`;
+}