import Foundation
import RastrilloApple
import Testing

@testable import SheetsKit

// B12 and its review (#35). The server says how many versions a write
// consumed (`stamps`); accept() refetches only when the version moved
// further than that, so a multi-cell batch applies in place. Stampless
// responses (format, size, snapshot) allow one. The server-side proof,
// against real responses, is TestNativeVersionContractAgainstRealResponses.
//
// The client points at a closed port, so an attempted refetch shows as a
// connection error and leaves the incremental cells unapplied.
@MainActor private func gapModel(version: UInt64) -> SheetModel {
  let model = SheetModel(client: NativeHTTP(origin: URL(string: "http://127.0.0.1:1")!))
  model.page = SheetPage(
    Sheet: SheetSummary(ID: 1, Title: "Fixture", TabID: 1, TabName: "Sheet 1"), Rows: 10, Cols: 5,
    Truncated: false, MayWrite: true, MayComment: true, MayShare: false, FillSwatches: [],
    InkSwatches: [], NumberFormats: [], Warned: nil)
  model.version = version
  model.error = ""
  return model
}

@MainActor @Test func stampedBatchAppliesWithoutRefetch() async {
  let model = gapModel(version: 5)
  // Three typed cells (versions 6, 7, 8) plus one formula they changed.
  await model.received(
    SheetEvent(
      name: "cells",
      data: #"{"version":8,"stamps":3,"cells":[{"r":0,"c":0,"raw":"1","display":"1"},{"r":1,"c":0,"raw":"2","display":"2"},{"r":2,"c":0,"raw":"3","display":"3"},{"r":3,"c":0,"raw":"=SUM(A1:A3)","display":"6","derived":true}]}"#
    ), source: model.grid)
  #expect(model.error == "", "a stamped batch attempted a refetch: \(model.error)")
  #expect(model.version == 8)
  #expect(model.cells[Coordinate(r: 2, c: 0)]?.raw == "3")
  #expect(model.cells[Coordinate(r: 3, c: 0)]?.display == "6")
}

@MainActor @Test func versionGapBeyondTheStampsStillRefetches() async {
  let model = gapModel(version: 5)
  // Two stamps ending at 9, so versions 6 and 7 were missed.
  await model.received(
    SheetEvent(
      name: "cells",
      data: #"{"version":9,"stamps":2,"cells":[{"r":0,"c":0,"raw":"1","display":"1"},{"r":1,"c":0,"raw":"2","display":"2"}]}"#
    ), source: model.grid)
  #expect(model.error != "", "a real gap was applied incrementally instead of refetched")
  #expect(model.version == 5)
  #expect(model.cells[Coordinate(r: 0, c: 0)] == nil)
}

@MainActor @Test func formatCellsDoNotWidenTheAcceptedJump() async {
  let model = gapModel(version: 5)
  // A format over four cells consumes no stamp; version 7 means a missed
  // edit, however many cells the format response lists.
  let cells = (0..<4).map { Cell(r: $0, c: 0, raw: "", display: "") }
  await model.accept(GridResponse(version: 7, cells: cells))
  #expect(model.error != "")
  #expect(model.version == 5)
}

@MainActor @Test func singleStepsAndStamplessResponsesStillApply() async {
  let model = gapModel(version: 5)
  await model.accept(GridResponse(version: 6, cells: [Cell(r: 0, c: 0, raw: "x", display: "x")], stamps: 1))
  // A format right after reports the next stamp: one ahead, no stamps.
  await model.accept(GridResponse(version: 7, cells: [Cell(r: 0, c: 0, raw: "x", display: "x")]))
  #expect(model.error == "")
  #expect(model.version == 7)
  #expect(model.cells[Coordinate(r: 0, c: 0)]?.raw == "x")
}