package fejkdata

import "testing"

// TestRootReferenceAcrossFolders is the headline case: a category in one folder
// pulls a value from another via a {..path} reference resolved from the data root.
func TestRootReferenceAcrossFolders(t *testing.T) {
	dir := writeData(t, map[string]string{
		"en_US/person":   `["Pat Smith"]`,
		"sv_SE/greeting": `{"format":"Hej, {..en_US.person}!"}`,
	})
	f := newFejkdata(t, dir, WithSeed(1))
	if got := fake(t, f, "sv_SE.greeting"); got != "Hej, Pat Smith!" {
		t.Fatalf("greeting = %q, want \"Hej, Pat Smith!\"", got)
	}
}

// TestReferenceIntoAField reaches a field inside a referenced category, crossing
// a single-variant choice and then a template field (..who.last).
func TestReferenceIntoAField(t *testing.T) {
	dir := writeData(t, map[string]string{
		"who":  `[{"format":"{first} {last}","first":["Ada"],"last":["Byron"]}]`,
		"card": `{"format":"signed {..who.last}"}`,
	})
	f := newFejkdata(t, dir, WithSeed(1))
	if got := fake(t, f, "card"); got != "signed Byron" {
		t.Fatalf("card = %q, want \"signed Byron\"", got)
	}
}

// TestReferenceInAlternation lets a reference stand as one arm of a {a|..b}
// alternation, so a field and a cross-file value share one slot.
func TestReferenceInAlternation(t *testing.T) {
	dir := writeData(t, map[string]string{
		"far":  `["X"]`,
		"near": `{"format":"{here|..far}","here":["H"]}`,
	})
	f := newFejkdata(t, dir, WithSeed(2))
	seen := map[string]bool{}
	for i := 0; i < 100; i++ {
		seen[fake(t, f, "near")] = true
	}
	if !seen["H"] || !seen["X"] || len(seen) != 2 {
		t.Fatalf("alternation produced %v, want both H and X", seen)
	}
}

// TestReferenceCombinesLoadedPaths is the point of references over the merge
// model: data layered from two dirs can point at each other through the root.
func TestReferenceCombinesLoadedPaths(t *testing.T) {
	a := writeData(t, map[string]string{"en_US/word": `["river"]`})
	b := writeData(t, map[string]string{"mine/slug": `{"format":"the-{..en_US.word}"}`})
	f := newFejkdataN(t, []string{a, b}, WithSeed(1))
	if got := fake(t, f, "mine.slug"); got != "the-river" {
		t.Fatalf("slug = %q, want the-river", got)
	}
}

// TestReferenceChain follows a reference to a node that is itself a reference, so
// linking order cannot matter.
func TestReferenceChain(t *testing.T) {
	dir := writeData(t, map[string]string{
		"a": `{"format":"{..b}"}`,
		"b": `{"format":"{..c}"}`,
		"c": `["deep"]`,
	})
	f := newFejkdata(t, dir, WithSeed(1))
	if got := fake(t, f, "a"); got != "deep" {
		t.Fatalf("a = %q, want deep", got)
	}
}

// TestReferenceErrors lists the references New must reject up front, so a bad path
// fails at load, never at a random render.
func TestReferenceErrors(t *testing.T) {
	cases := map[string]map[string]string{
		"missing target": {"card": `{"format":"{..nope.gone}"}`},
		"folder target":  {"en_US/word": `["w"]`, "card": `{"format":"{..en_US}"}`},
		"multi-variant on the path": {
			"who":  `[{"format":"{f}","f":["1"]},{"format":"{f}","f":["2"]}]`,
			"card": `{"format":"{..who.f}"}`,
		},
		"empty reference path": {"card": `{"format":"{..}"}`},
		// A reference that leads back to its own value never terminates at render,
		// so New must reject the cycle up front (direct, mutual, or chained).
		"direct cycle": {"a": `{"format":"x{..a}"}`},
		"mutual cycle": {"a": `{"format":"{..b}"}`, "b": `{"format":"{..a}"}`},
		"chain cycle":  {"a": `{"format":"{..b}"}`, "b": `{"format":"{..c}"}`, "c": `{"format":"{..a}"}`},
		// calc renders its operands, so a cycle through one must be caught too.
		"calc operand cycle": {"x": `{"format":"{calc(y)}","y":[{"format":"{..x}"}]}`},
		// A field its parent's format never renders is still reachable by dot path,
		// so a cycle hiding in one must fail at New rather than at render.
		"cycle in an unrendered field": {"cat": `{"format":"hi","x":{"format":"{..cat.x}"}}`},
		"mutual cycle between unrendered fields": {
			"cat": `{"format":"hi","x":{"format":"{..cat.y}"},"y":{"format":"{..cat.x}"}}`,
		},
		"cycle in an unrendered field of a choice arm": {
			"cat": `[{"format":"hi","x":{"format":"{..cat.x}"}}]`,
		},
		// The shipped layout puts categories in folders, so a cycle one level down
		// is the common case, not an edge case.
		"cycle in a subfolder":            {"sv_SE/a": `{"format":"x{..sv_SE.a}"}`},
		"mutual cycle within a subfolder": {"sv_SE/a": `{"format":"{..sv_SE.b}"}`, "sv_SE/b": `{"format":"{..sv_SE.a}"}`},
		"mutual cycle across two folders": {"en_US/a": `{"format":"{..sv_SE.b}"}`, "sv_SE/b": `{"format":"{..en_US.a}"}`},
		// ".." is reserved for bound references, so an authored key using it would
		// name a node nothing can reach and nothing would validate.
		"field key using the reference prefix": {"cat": `{"format":"hi","..x":{"format":"{..nope}"}}`},
	}
	for name, files := range cases {
		if _, err := New([]string{writeData(t, files)}); err == nil {
			t.Errorf("%s: New = nil error, want a reference error", name)
		}
	}
}

// TestDotPrefixedDataEntriesAreSkipped pins what a leading dot means on disk: the
// entry is hidden, not data, so a data directory can also be a checkout. A name
// starting with the reference prefix is covered by that same rule, since ".."
// starts with "." — it is skipped, not rejected.
func TestDotPrefixedDataEntriesAreSkipped(t *testing.T) {
	f := newFejkdata(t, writeData(t, map[string]string{
		"sv_SE/ok":     `["fine"]`,
		"sv_SE/..bad":  `{"format":"{..nope}"}`,
		"sv_SE/..y/ct": `{"format":"{..nope}"}`,
		".git/config":  `["not data"]`,
	}), WithSeed(1))
	if got := f.List(); len(got) != 1 || got[0] != "sv_SE.ok" {
		t.Fatalf("List() = %v, want only sv_SE.ok", got)
	}
}

// TestReferenceFromUnrenderedFieldTerminates guards the cycle check against
// over-rejecting: a field the format never renders may point back at its own
// category, which terminates, and stays renderable by path.
func TestReferenceFromUnrenderedFieldTerminates(t *testing.T) {
	dir := writeData(t, map[string]string{"cat": `{"format":"hi","x":{"format":"see {..cat}"}}`})
	f := newFejkdata(t, dir, WithSeed(1))
	if got := fake(t, f, "cat"); got != "hi" {
		t.Fatalf("cat = %q, want hi", got)
	}
	if got := fake(t, f, "cat.x"); got != "see hi" {
		t.Fatalf("cat.x = %q, want \"see hi\"", got)
	}
}

// TestNewErrorIsDeterministic pins one message per broken data set: map iteration
// order must not decide which of several problems the user is told about, whether
// they sit in separate categories or in one template's fields.
func TestNewErrorIsDeterministic(t *testing.T) {
	cases := map[string]map[string]string{
		"three bad references": {
			"a": `{"format":"{..nope.one}"}`,
			"b": `{"format":"{..nope.two}"}`,
			"c": `{"format":"{..nope.three}"}`,
		},
		"two bad fields in one template": {
			"cat": `{"format":"hi","aaa":{"no":1},"zzz":{"no":2}}`,
		},
	}
	for name, files := range cases {
		dir := writeData(t, files)
		var first string
		for i := 0; i < 50; i++ {
			_, err := New([]string{dir})
			if err == nil {
				t.Fatalf("%s: New = nil error, want a load error", name)
			}
			if i == 0 {
				first = err.Error()
				continue
			}
			if err.Error() != first {
				t.Fatalf("%s: New error varies between runs:\n  %s\n  %s", name, first, err.Error())
			}
		}
		t.Logf("%s -> %s", name, first)
	}
}

// TestNewErrorPathIsCanonical pins the node path a load error names: a choice arm
// adds no segment, and a bound {..path} reference is not a containment segment at
// all, so a bad reference is reported against the node that holds it.
func TestNewErrorPathIsCanonical(t *testing.T) {
	cases := []struct {
		name  string
		files map[string]string
		want  string
	}{
		{
			"cycle inside a choice arm",
			map[string]string{"cat": `[{"format":"hi","x":{"format":"{..cat.x}"}}]`},
			"fejkdata: reference cycle: cat.x -> ..cat.x",
		},
		{
			"bad reference reached through another reference",
			map[string]string{"a": `{"format":"{..b}"}`, "b": `{"format":"{..nope}"}`},
			`fejkdata: b: reference {..nope}: no entry "nope"`,
		},
	}
	for _, c := range cases {
		_, err := New([]string{writeData(t, c.files)})
		if err == nil {
			t.Errorf("%s: New = nil error", c.name)
			continue
		}
		if err.Error() != c.want {
			t.Errorf("%s:\n  got  %s\n  want %s", c.name, err, c.want)
		}
	}
}