package api

import (
	"strings"
	"testing"
)

const fullEditBody = `{"revision":3,"title":"Notatka","type":"notatka","body":"Tekst","source":null,"url":null,"meeting_id":null,"tags":["lektura"]}`

// TestDecodeMaterialEdit checks the student edit body (D-09): every key is
// required, revision, title, type and tags may not be null, and unknown keys
// such as course_id or published_at are refused.
func TestDecodeMaterialEdit(t *testing.T) {
	in, errs, err := decodeMaterialEdit([]byte(fullEditBody))
	if err != nil {
		t.Fatal(err)
	}
	if len(errs) != 0 {
		t.Errorf("full body errors = %v, want none", errs)
	}
	if in.Revision == nil || *in.Revision != 3 || deref(in.Title) != "Notatka" || in.Tags == nil || len(*in.Tags) != 1 {
		t.Errorf("full body decoded to %+v", in)
	}
	for _, key := range materialEditKeys {
		raw := dropKey(t, fullEditBody, key)
		_, errs, err := decodeMaterialEdit([]byte(raw))
		if err != nil {
			t.Errorf("without %s: decode error %v", key, err)
			continue
		}
		if _, ok := errs[key]; !ok || len(errs) != 1 {
			t.Errorf("without %s: errors = %v, want one on %s", key, errs, key)
		}
	}
	for _, key := range []string{"revision", "title", "type", "tags"} {
		raw := nullKey(t, fullEditBody, key)
		_, errs, err := decodeMaterialEdit([]byte(raw))
		if err != nil {
			t.Errorf("null %s: decode error %v", key, err)
			continue
		}
		if _, ok := errs[key]; !ok || len(errs) != 1 {
			t.Errorf("null %s: errors = %v, want one on %s", key, errs, key)
		}
	}
	for _, key := range []string{"body", "source", "url", "meeting_id"} {
		_, errs, err := decodeMaterialEdit([]byte(nullKey(t, fullEditBody, key)))
		if err != nil || len(errs) != 0 {
			t.Errorf("null %s = %v %v, want no error", key, errs, err)
		}
	}
	for _, extra := range []string{`"course_id":1`, `"published_at":null`, `"author_user_id":2`, `"is_private":true`, `"share_user_ids":[]`} {
		raw := strings.TrimSuffix(fullEditBody, "}") + "," + extra + "}"
		if _, _, err := decodeMaterialEdit([]byte(raw)); err == nil {
			t.Errorf("body with %s decoded, want an unknown-field error", extra)
		}
	}
	if _, _, err := decodeMaterialEdit([]byte(`[1]`)); err == nil {
		t.Error("an array body decoded, want an error")
	}
}

// dropKey removes key and its value from the flat JSON object raw.
func dropKey(t *testing.T, raw, key string) string {
	t.Helper()
	parts := splitTop(raw)
	out := make([]string, 0, len(parts))
	for _, p := range parts {
		if !strings.HasPrefix(p, `"`+key+`":`) {
			out = append(out, p)
		}
	}
	if len(out) == len(parts) {
		t.Fatalf("key %s not in %s", key, raw)
	}
	return "{" + strings.Join(out, ",") + "}"
}

// nullKey sets key to null in the flat JSON object raw.
func nullKey(t *testing.T, raw, key string) string {
	t.Helper()
	parts := splitTop(raw)
	found := false
	for i, p := range parts {
		if strings.HasPrefix(p, `"`+key+`":`) {
			parts[i] = `"` + key + `":null`
			found = true
		}
	}
	if !found {
		t.Fatalf("key %s not in %s", key, raw)
	}
	return "{" + strings.Join(parts, ",") + "}"
}

// splitTop splits a flat JSON object into its "key":value members, keeping
// commas inside arrays.
func splitTop(raw string) []string {
	inner := strings.TrimSuffix(strings.TrimPrefix(raw, "{"), "}")
	var parts []string
	depth, start := 0, 0
	for i, c := range inner {
		switch c {
		case '[':
			depth++
		case ']':
			depth--
		case ',':
			if depth == 0 {
				parts = append(parts, inner[start:i])
				start = i + 1
			}
		}
	}
	return append(parts, inner[start:])
}

// TestNormalizeBody checks the body normalisation of the edit route (A6):
// LF line ends, no surrounding blank lines, one trailing newline, and an
// empty or whitespace-only body as null.
func TestNormalizeBody(t *testing.T) {
	s := func(v string) *string { return &v }
	cases := []struct {
		name string
		in   *string
		want *string
	}{
		{"nil", nil, nil},
		{"empty", s(""), nil},
		{"whitespace", s(" \n\t\r\n "), nil},
		{"crlf", s("a\r\nb\r\n"), s("a\nb\n")},
		{"cr", s("a\rb"), s("a\nb\n")},
		{"blank lines around", s("\n\n# Tytuł\n\ntekst\n\n\n"), s("# Tytuł\n\ntekst\n")},
		{"no newline", s("tekst"), s("tekst\n")},
		{"already normal", s("tekst\n"), s("tekst\n")},
	}
	for _, tc := range cases {
		got := normalizeBody(tc.in)
		switch {
		case tc.want == nil && got != nil:
			t.Errorf("%s: normalizeBody = %q, want nil", tc.name, *got)
		case tc.want != nil && (got == nil || *got != *tc.want):
			t.Errorf("%s: normalizeBody = %v, want %q", tc.name, got, *tc.want)
		}
	}
}