package check_test

import (
	"os"
	"path/filepath"
	"strings"
	"testing"

	"git.vakhrushev.me/av/convy/internal/check"
	"git.vakhrushev.me/av/convy/internal/suite"
)

// The fixtures below stay in Russian on purpose: they are the data under test,
// written in the natural language the suite declares. Only the tool's own text
// is English.

// versionLine is the language version line. It lists the key words of the
// suite, which makes it the only place lawfully carrying modal words outside a
// rule.
const versionLine = `Ключевые слова ДОЛЖЕН, НЕ ДОЛЖЕН, СЛЕДУЕТ, НЕ СЛЕДУЕТ, ДОПУСКАЕТСЯ и метки
ПОЧЕМУ, ПРИМЕРЫ, МЕХАНИЗИРОВАНО и СНЯТО толкуются как описано в языке
конвенций версии 1 — тогда и только тогда, когда написаны заглавными.`

const baseManifest = `
[language]
version = 1
description = "LANGUAGE.md"
reading = "READING.md"

[topics.live]
time = "время: хранение, зоны, форматы"

[topics.retired]

[prefixes.live]
TIME = "conventions/time.md"

[prefixes.retired]
`

const baseTime = `---
topic: time
prefix: TIME
---

# Время

Как приложение записывает моменты.

` + versionLine + `

## Правила

### TIME-1. Момент записывается в UTC

**ДОЛЖЕН.** Момент времени записывается с суффиксом Z.

**ПОЧЕМУ.** Без явного смещения не видно, в какой зоне запись сделана.
`

// files is the content of a suite: a path from the root mapped to the text of
// the file. An empty string means "no such file": that is how a test drops a
// file the base fixture provides.
type files map[string]string

func base() files {
	return files{
		"suite.toml":          baseManifest,
		"LANGUAGE.md":         "# Язык конвенций\n\nОписание языка.\n",
		"READING.md":          "# Как читать конвенцию\n\nКоротко.\n",
		"conventions/time.md": baseTime,
	}
}

// run writes a suite into a temporary directory and runs the checks over it.
func run(t *testing.T, f files) []check.Finding {
	t.Helper()
	root := t.TempDir()
	for name, content := range f {
		if content == "" {
			continue
		}
		path := filepath.Join(root, filepath.FromSlash(name))
		if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
			t.Fatal(err)
		}
		if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
			t.Fatal(err)
		}
	}
	s, err := suite.Load(root)
	if err != nil {
		t.Fatalf("loading the suite: %v", err)
	}
	return check.Suite(s).Findings()
}

func messages(findings []check.Finding) string {
	var b strings.Builder
	for _, f := range findings {
		b.WriteString(f.Path)
		b.WriteString(": ")
		b.WriteString(f.Msg)
		b.WriteString("\n")
	}
	return b.String()
}

func TestCleanSuite(t *testing.T) {
	if got := run(t, base()); len(got) != 0 {
		t.Fatalf("a sound suite produced findings:\n%s", messages(got))
	}
}

// TestRuleHeadingIsNotAReference holds the line between a declaration and a
// reference. A heading with a foreign prefix is an error of form, and only
// that: there is nothing to resolve against the manifest, otherwise one typo
// would yield two findings about different things.
func TestRuleHeadingIsNotAReference(t *testing.T) {
	f := base()
	f["conventions/time.md"] = strings.Replace(baseTime, "### TIME-1.", "### GTIM-1.", 1)

	for _, got := range run(t, f) {
		if got.Family == check.Links {
			t.Errorf("a heading was parsed as a reference: %s", got.Msg)
		}
	}
}

// rule builds a whole rule so that tests do not repeat its form.
func rule(id, title, norm, rationale string) string {
	return "\n### " + id + ". " + title + "\n\n**ДОЛЖЕН.** " + norm + "\n\n**ПОЧЕМУ.** " + rationale + "\n"
}

func TestChecks(t *testing.T) {
	cases := []struct {
		name  string
		setup func(files)
		want  string
	}{{
		name: "front matter prefix diverges from the manifest",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime, "prefix: TIME", "prefix: GTIM", 1)
		},
		want: "the front matter declares prefix GTIM, while the manifest assigns TIME to this file",
	}, {
		name: "rule heading carries a foreign prefix",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime, "### TIME-1.", "### GTIM-1.", 1)
		},
		want: "the rule heading uses prefix GTIM, while the file owns TIME",
	}, {
		name: "numbering has a gap",
		setup: func(f files) {
			f["conventions/time.md"] = baseTime + rule("TIME-3", "Третье", "Норма.", "Причина.")
		},
		want: "numbering is not contiguous",
	}, {
		name: "a number is taken twice",
		setup: func(f files) {
			f["conventions/time.md"] = baseTime + rule("TIME-1", "Ещё раз первое", "Норма.", "Причина.")
		},
		want: "number TIME-1 is taken twice",
	}, {
		name: "rule without a rationale",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime,
				"**ПОЧЕМУ.** Без явного смещения не видно, в какой зоне запись сделана.", "", 1)
		},
		want: "has no ПОЧЕМУ block: the rationale is mandatory",
	}, {
		name: "rule with neither a norm nor a stub",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime,
				"**ДОЛЖЕН.** Момент времени записывается с суффиксом Z.", "Просто текст.", 1)
		},
		want: "has neither a norm block nor a СНЯТО stub",
	}, {
		name: "two norms under one number",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime,
				"**ПОЧЕМУ.**", "**СЛЕДУЕТ.** Вторая норма.\n\n**ПОЧЕМУ.**", 1)
		},
		want: "holds two norms (ДОЛЖЕН and СЛЕДУЕТ)",
	}, {
		name: "rationale precedes the norm",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime,
				"**ДОЛЖЕН.** Момент времени записывается с суффиксом Z.\n\n**ПОЧЕМУ.** Без явного смещения не видно, в какой зоне запись сделана.",
				"**ПОЧЕМУ.** Причина вперёд.\n\n**ДОЛЖЕН.** Момент времени записывается с суффиксом Z.", 1)
		},
		want: "the rationale precedes the norm",
	}, {
		name: "examples precede the rationale",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime,
				"**ПОЧЕМУ.**", "**ПРИМЕРЫ.** Иллюстрация.\n\n**ПОЧЕМУ.**", 1)
		},
		want: "the ПРИМЕРЫ block precedes the rationale",
	}, {
		name: "stub of a retired rule without a date",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime,
				"**ДОЛЖЕН.** Момент времени записывается с суффиксом Z.\n\n**ПОЧЕМУ.** Без явного смещения не видно, в какой зоне запись сделана.",
				"**СНЯТО.** Правило убрано за ненадобностью.", 1)
		},
		want: "carries no date of retirement",
	}, {
		name: "retired rule still holds a norm",
		setup: func(f files) {
			f["conventions/time.md"] = baseTime +
				"\n### TIME-2. Снятое\n\n**СНЯТО 2026-07-26.** Причина снятия.\n\n**ДОЛЖЕН.** Остаток нормы.\n"
		},
		want: "still holds a norm block",
	}, {
		name: "no language version line",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime, versionLine, "Просто вводная проза.", 1)
		},
		want: "holds no language version line",
	}, {
		name: "version line names a foreign version",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime, "конвенций версии 1", "конвенций версии 2", 1)
		},
		want: "does not name version 1",
	}, {
		name: "modal word outside a rule area",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime,
				"Как приложение записывает моменты.", "Приложение ДОЛЖЕН писать моменты.", 1)
		},
		want: "stands outside a rule area",
	}, {
		name: "word of a foreign vocabulary",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime,
				"**ПОЧЕМУ.** Без явного", "**ПОЧЕМУ.** Здесь MUST не к месту. Без явного", 1)
		},
		want: `the word MUST belongs to the "en" vocabulary`,
	}, {
		name: "reference to a rule that does not exist",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime,
				"Без явного смещения", "Смотри TIME-9. Без явного смещения", 1)
		},
		want: "reference TIME-9 does not resolve",
	}, {
		name: "reference to an unknown prefix",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime,
				"Без явного смещения", "Смотри ZZZZ-1. Без явного смещения", 1)
		},
		want: "prefix ZZZZ, which the suite manifest does not declare",
	}, {
		name: "topic not declared in the manifest",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime, "topic: time", "topic: clocks", 1)
		},
		want: `topic "clocks" is not declared`,
	}, {
		name: "topic listed among the retired ones",
		setup: func(f files) {
			f["suite.toml"] = strings.Replace(baseManifest,
				"[topics.retired]", `[topics.retired]`+"\ntime = \"снята 2026-07-01\"", 1)
		},
		want: "is listed both live and retired",
	}, {
		name: "live topic without layers",
		setup: func(f files) {
			f["suite.toml"] = strings.Replace(baseManifest,
				`time = "время: хранение, зоны, форматы"`,
				`time = "время"`+"\nlogging = \"логирование\"", 1)
		},
		want: `topic "logging" is declared live while the suite holds no layer of it`,
	}, {
		name: "declared file is missing",
		setup: func(f files) {
			f["suite.toml"] = strings.Replace(baseManifest,
				`TIME = "conventions/time.md"`,
				`TIME = "conventions/time.md"`+"\nSLOG = \"conventions/logging.md\"", 1)
		},
		want: `prefix SLOG is assigned to the file "conventions/logging.md", which the suite does not hold`,
	}, {
		name: "file not registered in the manifest",
		setup: func(f files) {
			f["conventions/logging.md"] = "---\ntopic: logging\nprefix: SLOG\n---\n\n# Логирование\n"
		},
		want: "not declared in the suite manifest",
	}, {
		name: "prefix starts with X",
		setup: func(f files) {
			f["suite.toml"] = strings.Replace(baseManifest,
				`TIME = "conventions/time.md"`, `XTIM = "conventions/time.md"`, 1)
			f["conventions/time.md"] = strings.ReplaceAll(baseTime, "TIME", "XTIM")
		},
		want: "reserved for the local rules of consumers",
	}, {
		name: "one file with two prefixes declared",
		setup: func(f files) {
			f["suite.toml"] = strings.Replace(baseManifest,
				`TIME = "conventions/time.md"`,
				`TIME = "conventions/time.md"`+"\nGTIM = \"conventions/time.md\"", 1)
		},
		want: "has several prefixes declared for it",
	}, {
		name: "unknown manifest key",
		setup: func(f files) {
			f["suite.toml"] = baseManifest + "\n[extra]\nkey = 1\n"
		},
		want: "is unknown to the tool",
	}, {
		name: "mechanization mark in convention text",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime,
				"Без явного смещения", "Правило МЕХАНИЗИРОВАНО линтером. Без явного смещения", 1)
		},
		want: "its place is the note of mechanization in the local part of the copy",
	}, {
		name: "canon path in convention text",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime,
				"Без явного смещения", "Смотри conventions/time.md. Без явного смещения", 1)
		},
		want: "the text holds the canon file path",
	}, {
		name: "document opens below level one",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime, "# Время", "## Время", 1)
		},
		want: "opens with a level-2 heading",
	}, {
		name: "second level-one heading",
		setup: func(f files) {
			f["conventions/time.md"] = baseTime + "\n# Ещё один заголовок\n\nПроза.\n"
		},
		want: "holds a second level-1 heading",
	}, {
		name: "heading skips a level",
		setup: func(f files) {
			f["conventions/time.md"] = strings.Replace(baseTime, "## Правила", "#### Правила", 1)
		},
		want: "skipping a level",
	}, {
		name: "scenario block opens with a foreign connective",
		setup: func(f files) {
			f["conventions/time.md"] = baseTime +
				"\nWHEN зависимость недоступна\nТОГДА запись ERROR\n"
		},
		want: `the scenario block opens with WHEN from the "en" vocabulary`,
	}, {
		name: "topic name is not usable as a file name",
		setup: func(f files) {
			// A bare non-ASCII key TOML rejects on its own; a quoted one
			// passes straight through, which is what the check is for.
			f["suite.toml"] = strings.Replace(baseManifest, "time =", `"время" =`, 1)
			f["conventions/time.md"] = strings.Replace(baseTime, "topic: time", "topic: время", 1)
		},
		want: "is not usable as a file name",
	}, {
		name: "topic name is not lower kebab-case",
		setup: func(f files) {
			f["suite.toml"] = strings.Replace(baseManifest, "time =", "Time_Zone =", 1)
			f["conventions/time.md"] = strings.Replace(baseTime, "topic: time", "topic: Time_Zone", 1)
		},
		want: "is not lower kebab-case",
	}, {
		name: "a second document without a topic",
		setup: func(f files) {
			f["suite.toml"] = strings.Replace(baseManifest,
				`TIME = "conventions/time.md"`,
				`TIME = "conventions/time.md"`+"\nMETA = \"GUIDE.md\"\nRULE = \"conventions/rules.md\"", 1)
			f["GUIDE.md"] = "---\nprefix: META\n---\n\n# Как мы ведём конвенции\n\n" + versionLine + "\n"
			f["conventions/rules.md"] = "---\nprefix: RULE\n---\n\n# Правила\n\n" + versionLine + "\n"
		},
		want: "more than one document without a topic",
	}, {
		name: "document without a topic carries layer keys",
		setup: func(f files) {
			f["suite.toml"] = strings.Replace(baseManifest,
				`TIME = "conventions/time.md"`,
				`TIME = "conventions/time.md"`+"\nGTIM = \"conventions/go.md\"", 1)
			f["conventions/go.md"] = "---\nprefix: GTIM\nlang: go\n---\n\n# Go\n\n" + versionLine + "\n"
		},
		want: "carries the keys of a layer",
	}}

	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			f := base()
			tc.setup(f)
			got := messages(run(t, f))
			if !strings.Contains(got, tc.want) {
				t.Fatalf("the check did not fire\nwanted: %s\ngot:\n%s", tc.want, got)
			}
		})
	}
}