1 files changed, 113 insertions, 0 deletions
diff --git a/src/eval.ts b/src/eval.ts
new file mode 100644
index 0000000..5e99282
--- /dev/null
+++ b/src/eval.ts
@@ -0,0 +1,113 @@
+import { CSSUnit, Expr } from './parser'
+import { match, matchString } from './utils/adt'
+
+export type EvalActions = {
+  addClass(id: string, classes: string): Promise<void>
+  removeClass(id: string, classes: string): Promise<void>
+  delay(num: number): Promise<void>
+  jsEval(js: string): Promise<any>
+  loadCssx(id: string, url: string): Promise<string>
+  getVariable(name: string): Promise<string | undefined>
+  updateVariable(id: string, varName: string, value: string): Promise<void>
+  setAttribute(name: string, value: string): Promise<void>
+  withEvent(fn: (e: any) => void): Promise<void>
+  getFormData(): Promise<FormData | undefined>
+  sendRequest(_: {
+    method: string
+    url: string
+    data: FormData | undefined
+  }): Promise<void>
+  // calculate ??
+}
+
+type EvalValue = string | undefined | void
+
+export const evalExpr = async (
+  expr: Expr,
+  actions: EvalActions,
+): Promise<EvalValue> =>
+  match<Promise<EvalValue>, Expr>(expr, {
+    Call: async ({ name, args }) => getFunctions(name, args, actions),
+    LiteralString: async s => s,
+    LiteralNumber: async ({ value, unit }) =>
+      matchString<number, CSSUnit>(unit, {
+        s: () => value * 1000,
+        _: () => value,
+      }).toString(),
+    Identifier: async s => s,
+    VarIdentifier: async s => s,
+    _: async _ => undefined,
+  })
+
+const getFunctions = (name: string, args: Expr[], actions: EvalActions) =>
+  matchString<Promise<EvalValue>>(name, {
+    'add-class': async () => {
+      const id = await evalExpr(args[0], actions)
+      const classes = await evalExpr(args[1], actions)
+      if (id && classes) {
+        await actions.addClass(id, classes)
+      }
+    },
+    'remove-class': async () => {
+      const id = await evalExpr(args[0], actions)
+      const classes = await evalExpr(args[1], actions)
+      if (id && classes) {
+        await actions.removeClass(id, classes)
+      }
+    },
+
+    delay: async () => {
+      const num = await evalExpr(args[0], actions)
+      console.log(num)
+      num && (await actions.delay(parseInt(num, 10)))
+    },
+    'js-eval': async () => {
+      const js = await evalExpr(args[0], actions)
+      js && (await actions.jsEval(js))
+    },
+
+    'load-cssx': async () => {
+      const id = await evalExpr(args[0], actions)
+      const url = await evalExpr(args[1], actions)
+      if (id && url) {
+        await actions.loadCssx(id, url)
+      }
+    },
+
+    var: async () => {
+      const varName = await evalExpr(args[0], actions)
+      const defaultValue = await evalExpr(args[1], actions)
+      return varName && (actions.getVariable(varName) ?? defaultValue)
+    },
+    update: async () => {
+      const id = await evalExpr(args[0], actions)
+      const varName = await evalExpr(args[1], actions)
+      const value = await evalExpr(args[2], actions)
+      if (id && varName && value) {
+        actions.updateVariable(id, varName, value)
+      }
+    },
+
+    'set-attr': async () => {
+      const name = await evalExpr(args[0], actions)
+      const value = await evalExpr(args[1], actions)
+      if (name && value) {
+        actions.setAttribute(name, value)
+      }
+    },
+    'prevent-default': async () => actions.withEvent(e => e.preventDefault()),
+
+    request: async () => {
+      const url = await evalExpr(args[0], actions)
+      const method = args[1]
+        ? (await evalExpr(args[1], actions)) ?? 'post'
+        : 'post'
+
+      if (url) {
+        const data = await actions.getFormData()
+        await actions.sendRequest({ method, url, data })
+      }
+    },
+
+    _: () => Promise.reject(new Error('not supposed to be here')),
+  })