import assert from "node:assert"
import test from "node:test"
import { FilePath, FullSlug, SimpleSlug } from "../../path"

type ContentLayout = "default" | "article" | "page"
import { evaluateExpression, valueToUnknown, EvalContext } from "./interpreter"
import { compileExpression } from "./ir"
import { parseExpressionSource } from "./parser"

const parseExpr = (source: string) => {
  const result = parseExpressionSource(source, "test")
  if (!result.program.body) {
    throw new Error(`expected expression for ${source}`)
  }
  return compileExpression(result.program.body)
}

const makeCtx = (): EvalContext => {
  const fileA = {
    slug: "a" as FullSlug,
    filePath: "a.md" as FilePath,
    frontmatter: { title: "A", pageLayout: "default" as ContentLayout },
    links: [] as SimpleSlug[],
  }
  const fileB = {
    slug: "b" as FullSlug,
    filePath: "b.md" as FilePath,
    frontmatter: { title: "B", pageLayout: "default" as ContentLayout },
    links: ["a"] as SimpleSlug[],
  }
  return { file: fileA, allFiles: [fileA, fileB] }
}

test("link equality resolves to file targets", () => {
  const expr = parseExpr('link("a") == file("a")')
  const value = valueToUnknown(evaluateExpression(expr, makeCtx()))
  assert.strictEqual(value, true)
})

test("link equality matches raw string targets", () => {
  const expr = parseExpr('link("a") == "a"')
  const value = valueToUnknown(evaluateExpression(expr, makeCtx()))
  assert.strictEqual(value, true)
})

test("date arithmetic handles month additions", () => {
  const expr = parseExpr('date("2025-01-01") + "1M"')
  const value = valueToUnknown(evaluateExpression(expr, makeCtx()))
  assert.ok(value instanceof Date)
  assert.strictEqual(value.toISOString().split("T")[0], "2025-02-01")
})

test("date subtraction returns duration in ms", () => {
  const expr = parseExpr('date("2025-01-02") - date("2025-01-01")')
  const value = valueToUnknown(evaluateExpression(expr, makeCtx()))
  assert.strictEqual(value, 86400000)
})

test("list summary helpers compute statistics", () => {
  const meanExpr = parseExpr("([1, 2, 3]).mean()")
  const medianExpr = parseExpr("([1, 2, 3]).median()")
  const stddevExpr = parseExpr("([1, 2, 3]).stddev()")
  const sumExpr = parseExpr("([1, 2, 3]).sum()")
  const ctx = makeCtx()
  assert.strictEqual(valueToUnknown(evaluateExpression(meanExpr, ctx)), 2)
  assert.strictEqual(valueToUnknown(evaluateExpression(medianExpr, ctx)), 2)
  assert.strictEqual(valueToUnknown(evaluateExpression(sumExpr, ctx)), 6)
  const stddev = valueToUnknown(evaluateExpression(stddevExpr, ctx))
  assert.strictEqual(typeof stddev, "number")
  if (typeof stddev === "number") {
    assert.ok(Math.abs(stddev - Math.sqrt(2 / 3)) < 1e-6)
  }
})