using System.Net;
using System.Text;
using System.Text.Json;
using System.Text.Json.Nodes;

using Microsoft.Playwright;

namespace decePubClient.E2E.Mobile
{
	// The phone sweep: a page measured and photographed one screen at a time down its main scroller (fit.js measures),
	// what doesn't fit kept as violations.json next to the screenshots, and a contact sheet of every route at every phone
	// in tests/e2e/out/mobile/<run>/index.html, for the eye.
	public static class Fit
	{
		public static readonly string Script = File.ReadAllText(Path.Combine(AppContext.BaseDirectory, "Mobile", "fit.js"));

		static readonly string RunDir = Path.Combine(TestsRoot(), "out", "mobile", DateTime.UtcNow.ToString("yyyyMMdd-HHmmss"));
		static readonly object SheetGate = new();

		static string TestsRoot()
		{
			var dir = AppContext.BaseDirectory;
			while (dir is not null && !File.Exists(Path.Combine(dir, "decePubClient.E2E.csproj")))
				dir = Path.GetDirectoryName(dir);
			return dir ?? throw new InvalidOperationException("decePubClient.E2E.csproj not found above the test output");
		}

		// what a sweep found, each finding once however many screens showed it
		public sealed class Report
		{
			readonly HashSet<string> seen = [];
			public List<JsonObject> Overflow { get; } = [];
			public List<JsonObject> Beyond { get; } = [];
			public List<JsonObject> Popovers { get; } = [];
			public List<JsonObject> Small { get; } = [];
			public List<JsonObject> Tiny { get; } = [];
			public int Screens { get; set; }

			public void Take(JsonNode measured, int screen)
			{
				Add(Overflow, measured["overflow"], "overflow", screen);
				Add(Beyond, measured["beyond"], "beyond", screen);
				Add(Popovers, measured["popovers"], "popover", screen);
				Add(Small, measured["small"], "small", screen);
				Add(Tiny, measured["tiny"], "tiny", screen);
			}

			void Add(List<JsonObject> into, JsonNode found, string kind, int screen)
			{
				foreach (var item in found!.AsArray().Select(i => i!.AsObject()))
				{
					var key = $"{kind}|{item["element"]}|{item["text"]}|{item["card"]}";
					if (!seen.Add(key))
						continue;
					var copy = Clean(item.DeepClone()).AsObject();
					copy["screen"] = screen;
					into.Add(copy);
				}
			}

			// Playwright marks the objects it hands back with $id; the findings don't need them
			static JsonNode Clean(JsonNode node)
			{
				if (node is JsonObject obj)
				{
					obj.Remove("$id");
					foreach (var (_, value) in obj)
						Clean(value);
				}
				else if (node is JsonArray array)
					foreach (var value in array)
						Clean(value);
				return node;
			}

			public string Json() => new JsonObject
			{
				["screens"] = Screens,
				["overflow"] = new JsonArray(Overflow.Select(o => (JsonNode)o.DeepClone()).ToArray()),
				["beyond"] = new JsonArray(Beyond.Select(o => (JsonNode)o.DeepClone()).ToArray()),
				["popovers"] = new JsonArray(Popovers.Select(o => (JsonNode)o.DeepClone()).ToArray()),
				["small"] = new JsonArray(Small.Select(o => (JsonNode)o.DeepClone()).ToArray()),
				["tiny"] = new JsonArray(Tiny.Select(o => (JsonNode)o.DeepClone()).ToArray())
			}.ToJsonString(new JsonSerializerOptions { WriteIndented = true });
		}

		public static Task Settle(IPage page) => page.EvaluateAsync("() => window.__fit.settle()");

		public static async Task<Report> Sweep(IPage page, Support.Phone phone, string slug, int screens)
		{
			var dir = Path.Combine(RunDir, phone.Key, slug);
			Directory.CreateDirectory(dir);
			var report = new Report();
			await Settle(page);
			await page.EvaluateAsync("() => window.__fit.primary()");
			for (var screen = 0; screen < screens; screen++)
			{
				var measured = JsonNode.Parse((await page.EvaluateAsync<JsonElement>("() => window.__fit.measure()")).GetRawText())!;
				report.Take(measured, screen);
				await page.ScreenshotAsync(new()
				{
					Path = Path.Combine(dir, $"{screen:00}.png"), Animations = ScreenshotAnimations.Disabled, Caret = ScreenshotCaret.Hide
				});
				report.Screens = screen + 1;
				if (!await page.EvaluateAsync<bool>("() => window.__fit.step(0.8)"))
					break;
				await Settle(page);
			}
			await File.WriteAllTextAsync(Path.Combine(dir, "violations.json"), report.Json());
			ContactSheet();
			return report;
		}

		// nothing scrolls sideways, nothing lies past the screen's sides, and every open menu, dialog or tip is whole
		public static void AssertFits(Report report)
		{
			var problems = report.Overflow.Select(o => $"sideways scroll in {o["element"]} (+{o["extra"]}px), furthest: {o["culprit"]?.ToJsonString()}")
				.Concat(report.Beyond.Select(b => $"past the screen: {b.ToJsonString()}"))
				.Concat(report.Popovers.Select(p => $"cut or outside: {p.ToJsonString()}"))
				.ToList();
			Assert.True(problems.Count == 0, $"{problems.Count} fit problems:\n" + string.Join("\n", problems.Take(12)));
		}

		// every target a thumb can reach has a 44px hit area, and no control's text is under 12px
		public static void AssertTouchable(Report report)
		{
			var problems = report.Small.Select(s => $"small target: {s.ToJsonString()}")
				.Concat(report.Tiny.Select(t => $"small text: {t.ToJsonString()}"))
				.ToList();
			Assert.True(problems.Count == 0, $"{problems.Count} touch problems:\n" + string.Join("\n", problems.Take(12)));
		}

		// every route as a row, every phone as a column: the first screen and how many findings
		static void ContactSheet()
		{
			lock (SheetGate)
			{
				var phones = Directory.GetDirectories(RunDir).Select(Path.GetFileName).Order().ToList();
				var routes = phones.SelectMany(p => Directory.GetDirectories(Path.Combine(RunDir, p)).Select(Path.GetFileName)).Distinct().Order().ToList();
				var html = new StringBuilder("<!doctype html><meta charset=utf-8><title>decePub on phones</title>")
					.Append("<style>body{font:13px system-ui;background:#222;color:#ddd}td{vertical-align:top;padding:6px}img{width:180px;display:block}")
					.Append("a{color:#9cf}.bad{color:#f88}</style><table><tr><th></th>");
				foreach (var phone in phones)
					html.Append("<th>").Append(WebUtility.HtmlEncode(phone)).Append("</th>");
				html.Append("</tr>");
				foreach (var route in routes)
				{
					html.Append("<tr><th>").Append(WebUtility.HtmlEncode(route)).Append("</th>");
					foreach (var phone in phones)
					{
						var dir = Path.Combine(RunDir, phone, route);
						html.Append("<td>");
						if (File.Exists(Path.Combine(dir, "violations.json")))
						{
							var found = JsonNode.Parse(File.ReadAllText(Path.Combine(dir, "violations.json")))!;
							var fit = found["overflow"]!.AsArray().Count + found["beyond"]!.AsArray().Count + found["popovers"]!.AsArray().Count;
							var touch = found["small"]!.AsArray().Count + found["tiny"]!.AsArray().Count;
							var link = $"{phone}/{route}";
							html.Append($"<a href=\"{link}/00.png\"><img src=\"{link}/00.png\"></a>")
								.Append($"<span class=\"{(fit + touch > 0 ? "bad" : "")}\">fit {fit} · touch {touch} · {found["screens"]} screens</span> ")
								.Append($"<a href=\"{link}/violations.json\">findings</a>");
						}
						html.Append("</td>");
					}
					html.Append("</tr>");
				}
				File.WriteAllText(Path.Combine(RunDir, "index.html"), html.Append("</table>").ToString());
			}
		}
	}
}