refactor(tui): extract shared frontend helpers (#37868)

packages/tui/src/model-preference.ts

@@ -0,0 +1,124 @@
+import { readJson, writeJsonAtomic } from "./util/persistence"
+import { isRecord } from "./util/record"
+
+export type ModelPreferenceModel = {
+  providerID: string
+  modelID: string
+}
+
+export type ModelPreference = {
+  recent: ModelPreferenceModel[]
+  favorite: ModelPreferenceModel[]
+  variant: Record<string, string | undefined>
+}
+
+export type ModelPreferenceDocument = Record<string, unknown> & ModelPreference
+
+function models(value: unknown) {
+  if (!Array.isArray(value)) return []
+  return value.flatMap((item): ModelPreferenceModel[] => {
+    if (!isRecord(item)) return []
+    if (typeof item.providerID !== "string" || item.providerID.length === 0) return []
+    if (typeof item.modelID !== "string" || item.modelID.length === 0) return []
+    return [{ providerID: item.providerID, modelID: item.modelID }]
+  })
+}
+
+function variants(value: unknown) {
+  if (!isRecord(value)) return {}
+  return Object.fromEntries(
+    Object.entries(value).flatMap(([key, item]) => {
+      if (key.length === 0 || typeof item !== "string" || item.length === 0) return []
+      const variant = normalizeModelVariant(item)
+      return variant === undefined ? [] : ([[key, variant]] as const)
+    }),
+  )
+}
+
+export function normalizeModelVariant(value: string | undefined) {
+  return value === "default" ? undefined : value
+}
+
+export function modelPreferenceKey(model: ModelPreferenceModel) {
+  return `${model.providerID}/${model.modelID}`
+}
+
+export function cycleModelVariant(current: string | undefined, variants: string[]) {
+  const named = variants.filter((variant) => variant !== "default")
+  if (named.length === 0) return undefined
+  const value = normalizeModelVariant(current)
+  if (value === undefined) return named[0]
+  const index = named.indexOf(value)
+  if (index === -1 || index === named.length - 1) return undefined
+  return named[index + 1]
+}
+
+export function decodeModelPreference(value: unknown): ModelPreferenceDocument {
+  const root = isRecord(value) ? value : {}
+  return {
+    ...root,
+    recent: models(root.recent),
+    favorite: models(root.favorite),
+    variant: variants(root.variant),
+  }
+}
+
+function preference(value: ModelPreferenceDocument): ModelPreference {
+  return {
+    recent: value.recent,
+    favorite: value.favorite,
+    variant: value.variant,
+  }
+}
+
+function patch(value: Partial<ModelPreference>) {
+  return {
+    ...(value.recent === undefined ? {} : { recent: models(value.recent) }),
+    ...(value.favorite === undefined ? {} : { favorite: models(value.favorite) }),
+    ...(value.variant === undefined ? {} : { variant: variants(value.variant) }),
+  }
+}
+
+export function createModelPreferenceRepository(filePath: string) {
+  const state = {
+    pending: Promise.resolve(),
+  }
+  const read = () =>
+    readJson<unknown>(filePath)
+      .then(decodeModelPreference)
+      .catch(() => decodeModelPreference(undefined))
+
+  function update(change: (current: ModelPreference) => Partial<ModelPreference>) {
+    const result = state.pending.then(async () => {
+      const current = await read()
+      const next = { ...current, ...patch(change(preference(current))) }
+      await writeJsonAtomic(filePath, next)
+    })
+    state.pending = result.catch(() => undefined)
+    return result
+  }
+
+  function load() {
+    return state.pending.then(read).then(preference)
+  }
+
+  return {
+    load,
+    patch(value: Partial<ModelPreference>) {
+      return update(() => value)
+    },
+    async resolveVariant(model: ModelPreferenceModel) {
+      return (await load()).variant[modelPreferenceKey(model)]
+    },
+    saveVariant(model: ModelPreferenceModel, value: string | undefined) {
+      const key = modelPreferenceKey(model)
+      const next = normalizeModelVariant(value)
+      return update((current) => {
+        const variant = { ...current.variant }
+        if (next === undefined) delete variant[key]
+        if (next !== undefined) variant[key] = next
+        return { variant }
+      })
+    },
+  }
+}