package docgen

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

// repoRoot is where the source paths in Sources are relative to.
func repoRoot(t *testing.T) string {
	t.Helper()
	_, file, _, ok := runtime.Caller(0)
	if !ok {
		t.Fatal("cannot locate this test")
	}
	return filepath.Join(filepath.Dir(file), "..", "..")
}

func sourcePaths(t *testing.T) []string {
	t.Helper()
	root := repoRoot(t)
	out := make([]string, len(Sources))
	for i, s := range Sources {
		out[i] = filepath.Join(root, s)
	}
	return out
}

func TestTheReferenceIsNotStale(t *testing.T) {
	// The whole point. A generated document that nobody regenerates is the
	// same lie as a hand-written one, arrived at more slowly: it describes the
	// configuration of some earlier week, and the setting somebody came to
	// look up is the one that is missing.
	blocks, err := Collect(sourcePaths(t))
	if err != nil {
		t.Fatal(err)
	}
	want := Render(blocks)

	path := filepath.Join(repoRoot(t), "docs", "reference.md")
	got, err := os.ReadFile(path)
	if err != nil {
		t.Fatalf("docs/reference.md is missing; run go generate ./...: %v", err)
	}
	if string(got) != want {
		t.Error("docs/reference.md no longer matches the configuration structs.\n" +
			"Run: go generate ./...")
	}
}

func TestEveryConfigurationFileIsListed(t *testing.T) {
	// Sources is a list, and a list is a thing to forget. A new file full of
	// settings would otherwise be absent from the reference with nothing
	// saying so — which is exactly the failure the reference exists to fix.
	root := repoRoot(t)
	var tagged []string
	err := filepath.Walk(filepath.Join(root, "internal"), func(p string, info os.FileInfo, err error) error {
		if err != nil || info.IsDir() || !strings.HasSuffix(p, ".go") || strings.HasSuffix(p, "_test.go") {
			return err
		}
		b, err := os.ReadFile(p)
		if err != nil {
			return err
		}
		if !strings.Contains(string(b), `koanf:"`) {
			return nil
		}
		rel, err := filepath.Rel(root, p)
		if err != nil {
			return err
		}
		tagged = append(tagged, rel)
		return nil
	})
	if err != nil {
		t.Fatal(err)
	}
	if len(tagged) == 0 {
		t.Fatal("found no configuration files at all, so this test proves nothing")
	}

	for _, f := range tagged {
		if slices.Contains(Sources, f) {
			continue
		}
		// Deliberately out: these hold koanf tags for structs an operator
		// never writes — inventory and catalog entries come from the API or
		// from a model file, not from the configuration.
		if slices.Contains(notReference, f) {
			continue
		}
		t.Errorf("%s declares configuration and is not in Sources or notReference", f)
	}
}

func TestADocumentedKeyKeepsItsComment(t *testing.T) {
	// The descriptions are the field comments, which is what makes the
	// reference worth reading rather than a list of names. A field whose
	// comment was the only explanation anywhere must not render blank.
	blocks, err := Collect(sourcePaths(t))
	if err != nil {
		t.Fatal(err)
	}
	var lease Field
	for _, b := range blocks {
		for _, f := range b.Fields {
			if f.Key == "lease_ttl" {
				lease = f
			}
		}
	}
	if lease.Key == "" {
		t.Fatal("lease_ttl is not in the reference")
	}
	if !strings.Contains(lease.Doc, "shared store") {
		t.Errorf("lease_ttl lost its explanation: %q", lease.Doc)
	}
}

func TestAFieldMarkedNotConfigurableIsLeftOut(t *testing.T) {
	// koanf:"-" means the field is carried in the struct and never read from
	// a file. Listing it would send somebody looking for a setting that does
	// not exist.
	blocks, err := Collect(sourcePaths(t))
	if err != nil {
		t.Fatal(err)
	}
	for _, b := range blocks {
		for _, f := range b.Fields {
			if f.Key == "-" || f.Key == "" {
				t.Errorf("%s lists a non-configurable field: %+v", b.Name, f)
			}
		}
	}
}

func TestTheSettingsScreensDescribeTheCode(t *testing.T) {
	// The screens list Reference; it must be what the structs say now.
	blocks, err := Collect(sourcePaths(t))
	if err != nil {
		t.Fatal(err)
	}
	have, err := os.ReadFile(filepath.Join(repoRoot(t), "internal", "docgen", "reference_gen.go"))
	if err != nil {
		t.Fatalf("reference_gen.go is missing; run go generate ./...: %v", err)
	}
	if string(have) != RenderGo(blocks) {
		t.Error("internal/docgen/reference_gen.go no longer matches the configuration structs; run go generate ./...")
	}
}