import assert from "node:assert"
import test from "node:test"
import { parseExpressionSource } from "./parser"

const isRecord = (value: unknown): value is Record<string, unknown> =>
  typeof value === "object" && value !== null

const strip = (node: unknown): unknown => {
  if (!isRecord(node)) return node
  const type = node.type
  if (type === "Identifier") {
    return { type, name: node.name }
  }
  if (type === "Literal") {
    const kind = node.kind
    const value = node.value
    const flags = node.flags
    return flags !== undefined ? { type, kind, value, flags } : { type, kind, value }
  }
  if (type === "UnaryExpr") {
    return { type, operator: node.operator, argument: strip(node.argument) }
  }
  if (type === "BinaryExpr" || type === "LogicalExpr") {
    return { type, operator: node.operator, left: strip(node.left), right: strip(node.right) }
  }
  if (type === "CallExpr") {
    const args = Array.isArray(node.args) ? node.args.map(strip) : []
    return { type, callee: strip(node.callee), args }
  }
  if (type === "MemberExpr") {
    return { type, object: strip(node.object), property: node.property }
  }
  if (type === "IndexExpr") {
    return { type, object: strip(node.object), index: strip(node.index) }
  }
  if (type === "ListExpr") {
    const elements = Array.isArray(node.elements) ? node.elements.map(strip) : []
    return { type, elements }
  }
  if (type === "ErrorExpr") {
    return { type, message: node.message }
  }
  return node
}

test("ebnf to ast mapping snapshots", () => {
  const cases: Array<{ source: string; expected: unknown }> = [
    {
      source: 'status == "done"',
      expected: {
        type: "BinaryExpr",
        operator: "==",
        left: { type: "Identifier", name: "status" },
        right: { type: "Literal", kind: "string", value: "done" },
      },
    },
    {
      source: "!done",
      expected: {
        type: "UnaryExpr",
        operator: "!",
        argument: { type: "Identifier", name: "done" },
      },
    },
    {
      source: "file.ctime",
      expected: {
        type: "MemberExpr",
        object: { type: "Identifier", name: "file" },
        property: "ctime",
      },
    },
    {
      source: 'note["my-field"]',
      expected: {
        type: "IndexExpr",
        object: { type: "Identifier", name: "note" },
        index: { type: "Literal", kind: "string", value: "my-field" },
      },
    },
    {
      source: "date(due) < today()",
      expected: {
        type: "BinaryExpr",
        operator: "<",
        left: {
          type: "CallExpr",
          callee: { type: "Identifier", name: "date" },
          args: [{ type: "Identifier", name: "due" }],
        },
        right: { type: "CallExpr", callee: { type: "Identifier", name: "today" }, args: [] },
      },
    },
    {
      source: "now() - file.ctime",
      expected: {
        type: "BinaryExpr",
        operator: "-",
        left: { type: "CallExpr", callee: { type: "Identifier", name: "now" }, args: [] },
        right: {
          type: "MemberExpr",
          object: { type: "Identifier", name: "file" },
          property: "ctime",
        },
      },
    },
    {
      source: "(pages * 2).round(0)",
      expected: {
        type: "CallExpr",
        callee: {
          type: "MemberExpr",
          object: {
            type: "BinaryExpr",
            operator: "*",
            left: { type: "Identifier", name: "pages" },
            right: { type: "Literal", kind: "number", value: 2 },
          },
          property: "round",
        },
        args: [{ type: "Literal", kind: "number", value: 0 }],
      },
    },
    {
      source: 'tags.containsAny("a","b")',
      expected: {
        type: "CallExpr",
        callee: {
          type: "MemberExpr",
          object: { type: "Identifier", name: "tags" },
          property: "containsAny",
        },
        args: [
          { type: "Literal", kind: "string", value: "a" },
          { type: "Literal", kind: "string", value: "b" },
        ],
      },
    },
    {
      source: "list(links).filter(value.isTruthy())",
      expected: {
        type: "CallExpr",
        callee: {
          type: "MemberExpr",
          object: {
            type: "CallExpr",
            callee: { type: "Identifier", name: "list" },
            args: [{ type: "Identifier", name: "links" }],
          },
          property: "filter",
        },
        args: [
          {
            type: "CallExpr",
            callee: {
              type: "MemberExpr",
              object: { type: "Identifier", name: "value" },
              property: "isTruthy",
            },
            args: [],
          },
        ],
      },
    },
    {
      source: '["a", "b", "c"].length',
      expected: {
        type: "MemberExpr",
        object: {
          type: "ListExpr",
          elements: [
            { type: "Literal", kind: "string", value: "a" },
            { type: "Literal", kind: "string", value: "b" },
            { type: "Literal", kind: "string", value: "c" },
          ],
        },
        property: "length",
      },
    },
    {
      source: "this.file.name",
      expected: {
        type: "MemberExpr",
        object: {
          type: "MemberExpr",
          object: { type: "Identifier", name: "this" },
          property: "file",
        },
        property: "name",
      },
    },
    {
      source: "a || b && c",
      expected: {
        type: "LogicalExpr",
        operator: "||",
        left: { type: "Identifier", name: "a" },
        right: {
          type: "LogicalExpr",
          operator: "&&",
          left: { type: "Identifier", name: "b" },
          right: { type: "Identifier", name: "c" },
        },
      },
    },
    {
      source: "values[0]",
      expected: {
        type: "IndexExpr",
        object: { type: "Identifier", name: "values" },
        index: { type: "Literal", kind: "number", value: 0 },
      },
    },
  ]

  for (const entry of cases) {
    const result = parseExpressionSource(entry.source)
    assert.strictEqual(result.diagnostics.length, 0)
    assert.deepStrictEqual(strip(result.program.body), entry.expected)
  }
})

test("syntax doc samples parse", () => {
  const samples = [
    'note["price"]',
    "file.size > 10",
    "file.hasLink(this.file)",
    'date("2024-12-01") + "1M" + "4h" + "3m"',
    "now() - file.ctime",
    "property[0]",
    'link("filename", icon("plus"))',
    'file.mtime > now() - "1 week"',
    '/abc/.matches("abcde")',
    'name.replace(/:/g, "-")',
    'values.filter(value.isType("number")).reduce(if(acc == null || value > acc, value, acc), null)',
  ]

  for (const source of samples) {
    const result = parseExpressionSource(source)
    assert.strictEqual(result.diagnostics.length, 0)
    assert.ok(result.program.body)
  }
})

test("string escapes are decoded", () => {
  const result = parseExpressionSource('"a\\n\\"b"')
  assert.strictEqual(result.diagnostics.length, 0)
  const literal = strip(result.program.body)
  if (!isRecord(literal)) {
    throw new Error("expected literal record")
  }
  assert.strictEqual(literal.type, "Literal")
  assert.strictEqual(literal.kind, "string")
  assert.strictEqual(literal.value, 'a\n"b')
})

test("parser reports errors and recovers", () => {
  const result = parseExpressionSource("status ==")
  assert.ok(result.diagnostics.length > 0)
  assert.ok(result.program.body)
})