package docsite

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

// fixtureModule is a small package exercising every declaration kind the
// identifier index records.
const fixtureModule = `package fixture

import "context"

// Bus is a generic-method host with a field and an embedded type.
type Bus struct {
	Name string
	Base
}

// Base is embedded in Bus.
type Base struct{ ID int }

// Ping is promoted to Bus.
func (Base) Ping() {}

// Handler is an interface.
type Handler interface {
	Handle(ctx context.Context) error
}

// Mode is a const.
const Mode = 1

// Default is a var.
var Default = &Bus{}

// New builds a Bus.
func New() *Bus { return &Bus{} }

// Fire is a generic method.
func (b *Bus) Fire[T any](v T) {}

// Close is a value-receiver method.
func (b Bus) Close() error { return nil }
`

func identFixture(t *testing.T, indexBody, readme string) string {
	t.Helper()
	return writeTree(t, map[string]string{
		"docs/site.yaml":                fixtureSite,
		"docs/index.md":                 page("Acme docs", "index", 0, indexBody),
		"docs/setup/start.md":           page("Start", "setup", 10, "Text.\n"),
		"modules/fixture/fixture.go":    fixtureModule,
		"modules/fixture/README.md":     "# fixture\n\nFixture does one thing.\n\n" + readme,
		"modules/fixture/sub/sub.go":    "package sub\n\n// Thing is exported.\ntype Thing struct{}\n",
		"modules/fixture/testdata/x.go": "package x\n\n// Hidden is never indexed.\nfunc Hidden() {}\n",
	})
}

// writeFile writes one file under root, creating its directory.
func writeFile(t *testing.T, root, name, body string) {
	t.Helper()
	p := filepath.Join(root, filepath.FromSlash(name))
	if err := os.MkdirAll(filepath.Dir(p), 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(p, []byte(body), 0o644); err != nil {
		t.Fatal(err)
	}
}

func TestIdentifierChecker(t *testing.T) {
	passing := strings.Join([]string{
		"- `fixture.New()` and `fixture.New`",
		"- `*fixture.Bus` and `fixture.Bus.Close`",
		"- `fixture.Bus.Fire[string](\"x\")` (generic method)",
		"- `fixture.Bus.Name` and `fixture.Bus.Base` (field, embedded)",
		"- `fixture.Bus.ID` and `fixture.Bus.Ping()` (promoted through Base)",
		"- `fixture.Handler.Handle` (interface method)",
		"- `fixture.Mode`, `fixture.Default`, `fixture.Bus.lowercase`",
		"- `sub.Thing` (sub-package)",
		"- `http.Handler`, `fields.yaml`, `acme.blog`, `summer.yaml`, `fixture.lower`",
		"",
		"```text",
		"fixture.NotChecked() // fenced blocks are skipped",
		"```",
		"",
	}, "\n")
	root := identFixture(t, passing, "## Usage\n\nCall `fixture.New()`.\n")
	problems, err := Check(Options{Root: root, Commands: fixtureCommands})
	if err != nil {
		t.Fatal(err)
	}
	if len(problems) > 0 {
		t.Fatalf("passing fixture: %q", problemLines(problems))
	}

	failing := passing + "Then `fixture.Missing` and `fixture.Bus.Nope`.\n\n`fixture.Hidden` lives in testdata.\n"
	root = identFixture(t, failing, "## Usage\n\nCall `fixture.Gone()`.\n")
	writeFile(t, root, "README.md", "# Root\n\nSee `x.Y`.\n\n`sub.Nothing`\n")
	problems, err = Check(Options{Root: root, Commands: fixtureCommands})
	if err != nil {
		t.Fatal(err)
	}
	want := []string{
		"README.md:5: identifier: sub.Nothing does not exist in modules/fixture/sub",
		"docs/index.md:22: identifier: fixture.Missing does not exist in modules/fixture",
		"docs/index.md:22: identifier: fixture.Bus.Nope does not exist in modules/fixture",
		"docs/index.md:24: identifier: fixture.Hidden does not exist in modules/fixture",
		"modules/fixture/README.md:7: identifier: fixture.Gone does not exist in modules/fixture",
	}
	if got := problemLines(problems); !slices.Equal(got, want) {
		t.Fatalf("problems =\n%s\nwant\n%s", strings.Join(got, "\n"), strings.Join(want, "\n"))
	}
}

func TestIdentifierIndexDuplicateName(t *testing.T) {
	root := writeTree(t, map[string]string{
		"modules/alpha/alpha.go":     "package alpha\n",
		"modules/alpha/util/util.go": "package util\n",
		"modules/beta/util/util.go":  "package util\n",
	})
	_, problems, err := buildIdentIndex(root)
	if err != nil {
		t.Fatal(err)
	}
	want := `modules/beta/util: identifier: package name "util" is used by modules/alpha/util and modules/beta/util; spans cannot tell them apart`
	if got := problemLines(problems); !slices.Equal(got, []string{want}) {
		t.Fatalf("problems = %q, want [%q]", got, want)
	}
}

// checkFixture writes a fixture tree around one index body and one
// fixture README section and returns its problem lines.
func checkFixture(t *testing.T, cmds *Commands, files map[string]string) []string {
	t.Helper()
	tree := map[string]string{
		"docs/site.yaml":             fixtureSite,
		"docs/setup/start.md":        page("Start", "setup", 10, "## First steps\n\nText.\n"),
		"modules/fixture/fixture.go": "package fixture\n",
		"modules/fixture/README.md":  "# fixture\n\nFixture does one thing.\n\n## Usage\n\nText.\n",
	}
	for k, v := range files {
		tree[k] = v
	}
	root := writeTree(t, tree)
	problems, err := Check(Options{Root: root, Commands: cmds})
	if err != nil {
		t.Fatal(err)
	}
	return problemLines(problems)
}

func assertProblems(t *testing.T, got, want []string) {
	t.Helper()
	if !slices.Equal(got, want) {
		t.Fatalf("problems =\n%s\nwant\n%s", strings.Join(got, "\n"), strings.Join(want, "\n"))
	}
}

func TestLinkChecker(t *testing.T) {
	good := "## Alpha\n\nSee [alpha](#alpha), [start](setup/start.md#first-steps), " +
		"[usage](../modules/fixture/README.md#usage), [web](https://example.com) and [mail](mailto:a@example.com).\n\n" +
		"![logo](https://example.com/logo.png)\n"
	assertProblems(t, checkFixture(t, fixtureCommands, map[string]string{
		"docs/index.md": page("Acme docs", "index", 0, good),
		"modules/fixture/README.md": "# fixture\n\nFixture does one thing.\n\n## Usage\n\n" +
			"See [start](../../docs/setup/start.md) and [source](fixture.go).\n",
	}), nil)

	bad := good + "\n[a](#nope) [b](setup/missing.md) [c](setup/start.md#nope)\n\n" +
		"[d](../modules/fixture/fixture.go) [e](/abs.html)\n"
	assertProblems(t, checkFixture(t, fixtureCommands, map[string]string{
		"docs/index.md": page("Acme docs", "index", 0, bad),
		"modules/fixture/README.md": "# fixture\n\nFixture does one thing.\n\n## Usage\n\n" +
			"See [other](../other/README.md) and [anchor](#missing).\n",
	}), []string{
		"docs/index.md:15: link: #nope not found in docs/index.md",
		"docs/index.md:15: link: setup/missing.md does not resolve",
		"docs/index.md:15: link: #nope not found in docs/setup/start.md",
		"docs/index.md:17: link: ../modules/fixture/fixture.go does not resolve",
		"docs/index.md:17: link: /abs.html does not resolve",
		"modules/fixture/README.md:7: link: ../other/README.md does not resolve",
		"modules/fixture/README.md:7: link: #missing not found in modules/fixture/README.md",
	})
}

func TestCommandChecker(t *testing.T) {
	example := "package main\n\nimport \"example.com/bonfire\"\n\n" +
		"var one = bonfire.Command{Name: \"acme:greet\"}\n\n" +
		"var many = []bonfire.Command{{Name: \"acme:list\"}, {Name: \"acme:sync\"}}\n"
	good := "Run `summer docs:build` or `$ summer make:plugin acme.blog`.\n\n" +
		"```sh\n$ summer docs:build --out site\nsummer --help\ncd app && summer make:plugin acme.blog\n" +
		"./bin/acme serve --addr :8080\n./bin/acme acme:greet blog\n./bin/acme acme:sync\n```\n\n" +
		"```text\nsummer not:checked\n```\n\n`summer.yaml` and `go install ./cmd/summer` are not commands.\n"
	files := map[string]string{
		"docs/index.md":                    page("Acme docs", "index", 0, good),
		"docs/examples/greet/main.go":      example,
		"examples/app/plugins/p/plugin.go": example,
	}
	assertProblems(t, checkFixture(t, fixtureCommands, files), nil)

	files["docs/index.md"] = page("Acme docs", "index", 0, good+
		"\nThen `summer no:such`.\n\n```bash\n./bin/acme docs:build\nsummer migrate\n```\n")
	files["modules/fixture/README.md"] = "# fixture\n\nFixture does one thing.\n\n## Usage\n\n```sh\n./bin/acme fixture:run\n```\n"
	assertProblems(t, checkFixture(t, fixtureCommands, files), []string{
		`docs/index.md:26: command: "no:such" is not a summer or application command`,
		`docs/index.md:29: command: "docs:build" is not a summer or application command`,
		`docs/index.md:30: command: "migrate" is not a summer or application command`,
		`modules/fixture/README.md:8: command: "fixture:run" is not a summer or application command`,
	})

	assertProblems(t, checkFixture(t, nil, map[string]string{
		"docs/index.md": page("Acme docs", "index", 0, "Text.\n"),
	}), []string{"docs: command: no command set supplied"})
}

func TestForbiddenChecker(t *testing.T) {
	// The forbidden words are built at run time so no test source names a
	// consuming application.
	name := "Fono" + "teka"
	accented := "P" + "Ł" + "Ý" + "tarium"
	assertProblems(t, checkFixture(t, fixtureCommands, map[string]string{
		"docs/index.md": page("Acme docs", "index", 0, "The host application.\n"),
	}), nil)

	got := checkFixture(t, fixtureCommands, map[string]string{
		"docs/index.md":       page("Acme docs", "index", 0, "The "+name+" app.\n"),
		"docs/setup/start.md": page("Start", "setup", 10, "## First steps\n\nSee "+accented+".\n"),
	})
	assertProblems(t, got, []string{
		"docs/index.md:9: forbidden: consuming-application name in output",
		"docs/setup/start.md:11: forbidden: consuming-application name in output",
	})

	site := strings.Replace(fixtureSite, "description: Acme docs.", "description: Docs for "+strings.ToLower(name)+".", 1)
	got = checkFixture(t, fixtureCommands, map[string]string{
		"docs/site.yaml": site,
		"docs/index.md":  page("Acme docs", "index", 0, "Text.\n"),
	})
	if !slices.Contains(got, "llms.txt:3: forbidden: consuming-application name in output") {
		t.Fatalf("output check missed llms.txt: %q", got)
	}
	for _, line := range got {
		if !strings.HasSuffix(line, ": forbidden: consuming-application name in output") ||
			strings.Contains(strings.ToLower(line), strings.ToLower(name)) {
			t.Fatalf("unexpected problem line %q", line)
		}
	}
}

func TestFencePolicy(t *testing.T) {
	readme := "# fixture\n\nFixture does one thing.\n\n## Usage of `fixture`\n\n```go\nfixture.Run()\n```\n\n> [!TIP]\n> Fine.\n"
	good := "## Plain heading\n\n> [!NOTE]\n> A note.\n\n> [!WARNING]\n> Careful.\n\n```text\nplain\n```\n\n" +
		"```yaml\nkey: value\n```\n\n```md\n> [!DANGER]\n```\n"
	assertProblems(t, checkFixture(t, fixtureCommands, map[string]string{
		"docs/index.md":             page("Acme docs", "index", 0, good),
		"modules/fixture/README.md": readme,
	}), nil)

	bad := good + "\n```go\nfmt.Println()\n```\n\n> [!DANGER]\n> Boom.\n\n## Use `fixture`\n\n## Zażółć\n\n## See [start](setup/start.md)\n"
	assertProblems(t, checkFixture(t, fixtureCommands, map[string]string{
		"docs/index.md":             page("Acme docs", "index", 0, bad),
		"modules/fixture/README.md": readme + "\n> [!CAUTION]\n> No.\n",
	}), []string{
		"docs/index.md:29: snippet: go code block has no src= reference",
		"docs/index.md:33: callout: unknown type DANGER (use NOTE, TIP or WARNING)",
		"docs/index.md:36: heading: headings must be plain ASCII text without links or code",
		"docs/index.md:38: heading: headings must be plain ASCII text without links or code",
		"docs/index.md:40: heading: headings must be plain ASCII text without links or code",
		"modules/fixture/README.md:14: callout: unknown type CAUTION (use NOTE, TIP or WARNING)",
	})
}