package check

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

	"amadan.net/rastrillo/fiesta"
	"amadan.net/rastrillo/fiesta/example"
)

// The seeded fixtures: the pages rastrillo's browser drives built by
// hand at the seed commit, written out once under testdata/fixtures/
// and listed in index.json by the file, builder and case they came
// from. A drive ported here reads its page through fixture rather
// than retyping it, so the page it drives is the page the rastrillo
// drive drove.

// fixtureRow is one entry of testdata/fixtures/index.json. A row
// names either a path under testdata/fixtures/ or an example state
// that carries the same markup; the two reference rows have no path.
type fixtureRow struct {
	File    string `json:"file"`
	Builder string `json:"builder"`
	Case    string `json:"case"`
	Path    string `json:"path"`
	Kind    string `json:"kind"`
	Request string `json:"request"`
	Example string `json:"example"`
	Note    string `json:"note"`
}

// fixtureDir is where the index and the files live, under check/.
const fixtureDir = "testdata/fixtures"

// fixtureIndex reads index.json.
func fixtureIndex(t *testing.T) []fixtureRow {
	t.Helper()
	b, err := os.ReadFile(filepath.Join(fixtureDir, "index.json"))
	if err != nil {
		t.Fatal(err)
	}
	var rows []fixtureRow
	if err := json.Unmarshal(b, &rows); err != nil {
		t.Fatalf("%s/index.json: %v", fixtureDir, err)
	}
	return rows
}

// fixture returns the contents of the fixture file the index lists for
// the {file, builder, case} row: the body or the whole document, as
// the row's kind says, exactly as the rastrillo builder wrote it. It fails
// the test when the row is missing, when the row names an example
// rather than a path, or when the file is absent.
func fixture(t *testing.T, file, builder, kase string) string {
	t.Helper()
	for _, r := range fixtureIndex(t) {
		if r.File != file || r.Builder != builder || r.Case != kase {
			continue
		}
		if r.Path == "" {
			t.Fatalf("fixture %s %s %q has no path (it names example %q); read it through the example package", file, builder, kase, r.Example)
		}
		b, err := os.ReadFile(filepath.Join(fixtureDir, filepath.FromSlash(r.Path)))
		if err != nil {
			t.Fatalf("fixture %s %s %q: %v", file, builder, kase, err)
		}
		return string(b)
	}
	t.Fatalf("fixture %s %s %q is not in %s/index.json", file, builder, kase, fixtureDir)
	return ""
}

// fixtureExample returns the markup of the example state the index
// names for the {file, builder, case} row: the two rows whose rastrillo
// page was a styleguide sample carry "example/state" instead of a
// path, and read through the example package. It fails the test when
// the row is missing, when the row names a path rather than an
// example, or when the state cannot be read.
func fixtureExample(t *testing.T, file, builder, kase string) string {
	t.Helper()
	for _, r := range fixtureIndex(t) {
		if r.File != file || r.Builder != builder || r.Case != kase {
			continue
		}
		if r.Example == "" {
			t.Fatalf("fixture %s %s %q names a path (%s), not an example; read it through fixture", file, builder, kase, r.Path)
		}
		name, state, ok := strings.Cut(r.Example, "/")
		if !ok {
			t.Fatalf("fixture %s %s %q names example %q, which is not example/state", file, builder, kase, r.Example)
		}
		markup, err := example.Markup(fiesta.FS(), name, state)
		if err != nil {
			t.Fatalf("fixture %s %s %q: %v", file, builder, kase, err)
		}
		return markup
	}
	t.Fatalf("fixture %s %s %q is not in %s/index.json", file, builder, kase, fixtureDir)
	return ""
}

// TestEveryFixtureRowResolves: every row that names a path names a
// file that exists and is not empty, and the rows without a path are
// the example references, which name an example. The count is floored
// at 100 so an index that lost its rows could not pass by listing
// nothing.
func TestEveryFixtureRowResolves(t *testing.T) {
	rows := fixtureIndex(t)
	if len(rows) < 100 {
		t.Fatalf("%s/index.json lists %d rows; the seed wrote 137", fixtureDir, len(rows))
	}
	seen := map[[3]string]bool{}
	for _, r := range rows {
		key := [3]string{r.File, r.Builder, r.Case}
		if seen[key] {
			t.Errorf("%s %s %q is listed twice", r.File, r.Builder, r.Case)
		}
		seen[key] = true
		if r.Path == "" {
			if r.Example == "" {
				t.Errorf("%s %s %q has neither a path nor an example", r.File, r.Builder, r.Case)
			}
			continue
		}
		info, err := os.Stat(filepath.Join(fixtureDir, filepath.FromSlash(r.Path)))
		if err != nil {
			t.Errorf("%s %s %q: %v", r.File, r.Builder, r.Case, err)
			continue
		}
		if info.Size() == 0 {
			t.Errorf("%s %s %q: %s is empty", r.File, r.Builder, r.Case, r.Path)
		}
		if got := fixture(t, r.File, r.Builder, r.Case); int64(len(got)) != info.Size() {
			t.Errorf("%s %s %q: fixture returned %d bytes of a %d-byte file", r.File, r.Builder, r.Case, len(got), info.Size())
		}
	}
}