// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: MIT

package interpres

import (
	"errors"
	"math"
	"strings"
	"testing"
	"time"
)

func TestParseScalars(t *testing.T) {
	tree, err := ParseMap([]byte(`
title = "interpres"
count = 42
ratio = 3.14
enabled = true
disabled = false
hexv = 0xFF
octv = 0o755
binv = 0b1010
grouped = 1_000_000
neg = -17
expv = 1e3
`))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}

	cases := map[string]any{
		"title":    "interpres",
		"count":    int64(42),
		"ratio":    3.14,
		"enabled":  true,
		"disabled": false,
		"hexv":     int64(255),
		"octv":     int64(493),
		"binv":     int64(10),
		"grouped":  int64(1000000),
		"neg":      int64(-17),
		"expv":     1000.0,
	}
	for k, want := range cases {
		if got := tree[k]; got != want {
			t.Errorf("%s = %#v (%T), want %#v (%T)", k, got, got, want, want)
		}
	}
}

func TestParseInfNan(t *testing.T) {
	tree, err := ParseMap([]byte("pos = inf\nneg = -inf\nbad = nan\n"))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	if v := tree["pos"].(float64); !math.IsInf(v, 1) {
		t.Errorf("pos = %v, want +Inf", v)
	}
	if v := tree["neg"].(float64); !math.IsInf(v, -1) {
		t.Errorf("neg = %v, want -Inf", v)
	}
	if v := tree["bad"].(float64); !math.IsNaN(v) {
		t.Errorf("bad = %v, want NaN", v)
	}
}

func TestParseStrings(t *testing.T) {
	tree, err := ParseMap([]byte(`
basic = "a\tb\nc"
literal = 'C:\path\no\escape'
quote = "say \"hi\""
unicode = "\u00e9"
`))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	if tree["basic"] != "a\tb\nc" {
		t.Errorf("basic = %q", tree["basic"])
	}
	if tree["literal"] != `C:\path\no\escape` {
		t.Errorf("literal = %q", tree["literal"])
	}
	if tree["quote"] != `say "hi"` {
		t.Errorf("quote = %q", tree["quote"])
	}
	if tree["unicode"] != "é" {
		t.Errorf("unicode = %q", tree["unicode"])
	}
}

func TestParseMultilineString(t *testing.T) {
	tree, err := ParseMap([]byte("text = \"\"\"\nfirst\nsecond\"\"\"\n"))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	if tree["text"] != "first\nsecond" {
		t.Errorf("text = %q, want %q", tree["text"], "first\nsecond")
	}
}

func TestParseMultilineLineEndingBackslash(t *testing.T) {
	tree, err := ParseMap([]byte("text = \"\"\"\\\n    one \\\n    two\"\"\"\n"))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	if tree["text"] != "one two" {
		t.Errorf("text = %q, want %q", tree["text"], "one two")
	}
}

func TestParseTablesAndDottedKeys(t *testing.T) {
	tree, err := ParseMap([]byte(`
owner.name = "Petr"

[server]
host = "localhost"
port = 9090

[server.tls]
enabled = true
`))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	server := tree["server"].(map[string]any)
	if server["host"] != "localhost" || server["port"] != int64(9090) {
		t.Errorf("server = %#v", server)
	}
	tls := server["tls"].(map[string]any)
	if tls["enabled"] != true {
		t.Errorf("tls = %#v", tls)
	}
	owner := tree["owner"].(map[string]any)
	if owner["name"] != "Petr" {
		t.Errorf("owner = %#v", owner)
	}
}

func TestParseArrayOfTables(t *testing.T) {
	tree, err := ParseMap([]byte(`
[[forms]]
name = "contact"

[[forms]]
name = "feedback"
`))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	forms := tree["forms"].([]map[string]any)
	if len(forms) != 2 {
		t.Fatalf("len(forms) = %d, want 2", len(forms))
	}
	if forms[0]["name"] != "contact" || forms[1]["name"] != "feedback" {
		t.Errorf("forms = %#v", forms)
	}
}

func TestParseArraysAndInlineTables(t *testing.T) {
	tree, err := ParseMap([]byte(`
ports = [80, 443]
mixed = [
  "a",
  "b",
]
point = { x = 1, y = 2 }
`))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	ports := tree["ports"].([]any)
	if len(ports) != 2 || ports[0] != int64(80) || ports[1] != int64(443) {
		t.Errorf("ports = %#v", ports)
	}
	mixed := tree["mixed"].([]any)
	if len(mixed) != 2 || mixed[0] != "a" || mixed[1] != "b" {
		t.Errorf("mixed = %#v", mixed)
	}
	point := tree["point"].(map[string]any)
	if point["x"] != int64(1) || point["y"] != int64(2) {
		t.Errorf("point = %#v", point)
	}
}

func TestParseDateTime(t *testing.T) {
	tree, err := ParseMap([]byte(`
offset = 1979-05-27T07:32:00Z
local = 1979-05-27T07:32:00
day = 1979-05-27
clock = 07:32:00
`))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	if off, ok := tree["offset"].(OffsetDateTime); !ok || off.Year() != 1979 || off.Hour() != 7 {
		t.Errorf("offset = %#v (%T)", tree["offset"], tree["offset"])
	}
	if ldt, ok := tree["local"].(LocalDateTime); !ok || ldt.Year() != 1979 || ldt.Hour() != 7 {
		t.Errorf("local = %#v (%T)", tree["local"], tree["local"])
	}
	if d, ok := tree["day"].(LocalDate); !ok || d.Month() != time.May || d.Day() != 27 {
		t.Errorf("day = %#v (%T)", tree["day"], tree["day"])
	}
	if clk, ok := tree["clock"].(LocalTime); !ok || clk.Hour() != 7 || clk.Minute() != 32 {
		t.Errorf("clock = %#v (%T)", tree["clock"], tree["clock"])
	}
}

func TestDateTimeFormats(t *testing.T) {
	tree, err := ParseMap([]byte("a = 1987-07-05 17:45:00Z\nb = 1987-07-05t17:45:00z\nc = 1977-12-21T10:32:00.555\n"))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	if _, ok := tree["a"].(OffsetDateTime); !ok {
		t.Errorf("a is %T, want OffsetDateTime", tree["a"])
	}
	if _, ok := tree["b"].(OffsetDateTime); !ok {
		t.Errorf("b is %T, want OffsetDateTime", tree["b"])
	}
	if _, ok := tree["c"].(LocalDateTime); !ok {
		t.Errorf("c is %T, want LocalDateTime", tree["c"])
	}
}

func TestUnmarshalDateTime(t *testing.T) {
	type Doc struct {
		Created time.Time `toml:"created"`
		Day     LocalDate `toml:"day"`
	}
	var d Doc
	if err := Unmarshal([]byte("created = 2026-06-20T10:00:00Z\nday = 2026-06-20\n"), &d); err != nil {
		t.Fatalf("unmarshal: %v", err)
	}
	if d.Created.Year() != 2026 || d.Created.Hour() != 10 {
		t.Errorf("Created = %v", d.Created)
	}
	if d.Day.Year() != 2026 || d.Day.Month() != time.June || d.Day.Day() != 20 {
		t.Errorf("Day = %v", d.Day)
	}
}

func TestUnmarshalStruct(t *testing.T) {
	type SMTP struct {
		Host string `toml:"host"`
		Port int    `toml:"port"`
	}
	type Form struct {
		Name    string   `toml:"name"`
		SMTP    SMTP     `toml:"smtp"`
		Origins []string `toml:"allowed_origins"`
	}
	type Config struct {
		Port  int    `toml:"port"`
		Forms []Form `toml:"forms"`
	}

	data := []byte(`
port = 8080

[[forms]]
name = "contact"
allowed_origins = ["https://example.com"]

[forms.smtp]
host = "smtp.example.com"
port = 587
`)

	var cfg Config
	if err := Unmarshal(data, &cfg); err != nil {
		t.Fatalf("unmarshal: %v", err)
	}
	if cfg.Port != 8080 {
		t.Errorf("Port = %d", cfg.Port)
	}
	if len(cfg.Forms) != 1 {
		t.Fatalf("len(Forms) = %d", len(cfg.Forms))
	}
	f := cfg.Forms[0]
	if f.Name != "contact" || f.SMTP.Host != "smtp.example.com" || f.SMTP.Port != 587 {
		t.Errorf("form = %#v", f)
	}
	if len(f.Origins) != 1 || f.Origins[0] != "https://example.com" {
		t.Errorf("origins = %#v", f.Origins)
	}
}

func TestUnmarshalCaseInsensitiveAndUntagged(t *testing.T) {
	type Config struct {
		Title string
		Count int
	}
	var cfg Config
	if err := Unmarshal([]byte("title = \"x\"\ncount = 3\n"), &cfg); err != nil {
		t.Fatalf("unmarshal: %v", err)
	}
	if cfg.Title != "x" || cfg.Count != 3 {
		t.Errorf("cfg = %#v", cfg)
	}
}

func TestDisallowUnknownFields(t *testing.T) {
	type C struct {
		Known string `toml:"known"`
	}
	data := []byte("known = \"x\"\nbogus = 1\n")

	var lenient C
	if err := Unmarshal(data, &lenient); err != nil {
		t.Fatalf("lenient unmarshal: %v", err)
	}

	var strict C
	err := NewDecoder().DisallowUnknownFields().Decode(data, &strict)
	if err == nil {
		t.Fatal("expected error for unknown field, got nil")
	}
}

func TestDisallowUnknownFieldsReportsSmallestKey(t *testing.T) {
	// Map iteration order is random, so the reported key must be chosen
	// deterministically: the smallest unknown key, whichever order the map
	// iterates in.
	type C struct {
		Known string `toml:"known"`
	}
	data := []byte("known = \"x\"\nzeta = 1\nalpha = 2\nmu = 3\n")
	for range 20 {
		var c C
		err := NewDecoder().DisallowUnknownFields().Decode(data, &c)
		if err == nil {
			t.Fatal("expected error for unknown fields")
		}
		if !strings.Contains(err.Error(), `unknown field "alpha"`) {
			t.Fatalf("err = %v, want the smallest unknown key alpha", err)
		}
	}
}

func TestSkippedFieldTag(t *testing.T) {
	type C struct {
		Keep string `toml:"keep"`
		Skip string `toml:"-"`
	}
	var c C
	if err := Unmarshal([]byte("keep = \"y\"\n"), &c); err != nil {
		t.Fatalf("unmarshal: %v", err)
	}
	if c.Keep != "y" || c.Skip != "" {
		t.Errorf("c = %#v", c)
	}
}

func TestSyntaxErrorReportsLine(t *testing.T) {
	_, err := ParseMap([]byte("a = 1\nb = \nc = 3\n"))
	if err == nil {
		t.Fatal("expected a syntax error")
	}
	se, ok := err.(*SyntaxError)
	if !ok {
		t.Fatalf("error is %T, want *SyntaxError", err)
	}
	if se.Line != 2 {
		t.Errorf("Line = %d, want 2", se.Line)
	}
}

func TestComments(t *testing.T) {
	tree, err := ParseMap([]byte(`
# a leading comment
key = "value" # trailing comment
# another
`))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	if tree["key"] != "value" {
		t.Errorf("key = %q", tree["key"])
	}
}

func TestDuplicateKeyRejected(t *testing.T) {
	_, err := ParseMap([]byte("a = 1\na = 2\n"))
	if err == nil {
		t.Fatal("expected duplicate key error")
	}
}

func TestRejectsInvalidNumbers(t *testing.T) {
	for _, tok := range []string{
		"01", "-01", "00",
		"1__0", "_1", "1_", "0x_1", "1_.0",
		"1.", ".5", "1.2.3", "1.e2",
		"1e", "1e+", "1e-", "0.0E", "0.0e", "1.5e+",
		"0x", "0o", "0b", "0b2", "0o8", "0xG",
		"+0x1",
	} {
		if _, err := ParseMap([]byte("v = " + tok + "\n")); err == nil {
			t.Errorf("%q: expected an error, got none", tok)
		}
	}
}

func TestParseRejectsOffsetOutOfRange(t *testing.T) {
	for _, tok := range []string{
		"1979-05-27T07:32:00+00:60",
		"1979-05-27T07:32:00-00:99",
		"1979-05-27T07:32:00+24:00",
		"1979-05-27T07:32:00+99:99",
	} {
		if _, err := ParseMap([]byte("v = " + tok + "\n")); err == nil {
			t.Errorf("%q: expected an error, got none", tok)
		}
	}
}

func TestParseAcceptsOffsetBounds(t *testing.T) {
	tree, err := ParseMap([]byte("a = 1979-05-27T07:32:00+23:59\nb = 1979-05-27T07:32:00-23:59\n"))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	a := tree["a"].(OffsetDateTime)
	if _, offset := a.Zone(); offset != 23*3600+59*60 {
		t.Fatalf("a offset = %d, want %d", offset, 23*3600+59*60)
	}
	b := tree["b"].(OffsetDateTime)
	if _, offset := b.Zone(); offset != -(23*3600 + 59*60) {
		t.Fatalf("b offset = %d", offset)
	}
}

func TestAcceptsNumberEdgeCases(t *testing.T) {
	cases := map[string]any{
		"0":           int64(0),
		"-0":          int64(0),
		"+99":         int64(99),
		"1_000":       int64(1000),
		"0xDEAD_BEEF": int64(0xDEADBEEF),
		"0o755":       int64(493),
		"0b1010":      int64(10),
		"0.0":         0.0,
		"3.14":        3.14,
		"6.022e23":    6.022e23,
		"1e10":        1e10,
		"1e0":         1.0,
		"1e06":        1e6,
		"0e00":        0.0,
		"2E-3":        2e-3,
		"-2.5E-3":     -2.5e-3,
	}
	for tok, want := range cases {
		tree, err := ParseMap([]byte("v = " + tok + "\n"))
		if err != nil {
			t.Errorf("%q: %v", tok, err)
			continue
		}
		if got := tree["v"]; got != want {
			t.Errorf("%q = %#v (%T), want %#v", tok, got, got, want)
		}
	}
}

func TestRejectsTableRedefinition(t *testing.T) {
	_, err := ParseMap([]byte("[a]\nx = 1\n\n[a]\ny = 2\n"))
	if err == nil {
		t.Fatal("expected a table-redefinition error")
	}
}

func TestAllowsImplicitThenExplicitTable(t *testing.T) {
	tree, err := ParseMap([]byte("[a.b]\nx = 1\n\n[a]\ny = 2\n"))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	a := tree["a"].(map[string]any)
	if a["y"] != int64(2) {
		t.Errorf("a.y = %#v", a["y"])
	}
	if b := a["b"].(map[string]any); b["x"] != int64(1) {
		t.Errorf("a.b.x = %#v", b["x"])
	}
}

func TestRejectsControlCharInString(t *testing.T) {
	if _, err := ParseMap([]byte("v = \"a\x01b\"\n")); err == nil {
		t.Fatal("expected a control-character error")
	}
}

func TestAllowsEscapedControlChar(t *testing.T) {
	tree, err := ParseMap([]byte(`v = "\u0000"`))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	if tree["v"] != "\x00" {
		t.Errorf("v = %q", tree["v"])
	}
}

func TestMultilineQuotesAtDelimiter(t *testing.T) {
	tree, err := ParseMap([]byte("a = '''''two quotes'''''\n"))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	if tree["a"] != "''two quotes''" {
		t.Errorf("a = %q", tree["a"])
	}
}

func TestRejectsInlineTableExtension(t *testing.T) {
	cases := map[string]string{
		"by header":      "a = { b = 1 }\n[a.c]\nx = 2\n",
		"by dotted key":  "a = { b = 1 }\na.c = 2\n",
		"header over it": "a = { b = 1 }\n[a]\nx = 2\n",
		// The frozen check must cover the intermediate steps of an array-of-tables
		// header, not only the leaf: [[a.b.c]] walks through a and a.b.
		"by nested array header": "a = { b = {} }\n[[a.b.c]]\nx = 2\n",
	}
	for name, doc := range cases {
		if _, err := ParseMap([]byte(doc)); err == nil {
			t.Errorf("%s: expected an inline-table extension error", name)
		}
	}
}

// A new element of an array of tables starts a fresh scope: sub-table headers,
// nested arrays of tables, and dotted-key paths recorded for the previous
// element must not block the same paths in the next one.
func TestArrayOfTablesFreshScopePerElement(t *testing.T) {
	cases := map[string]string{
		"nested array of tables": "[[a]]\n[[a.b]]\nx = 1\n[[a]]\n[a.b]\ny = 2\n",
		"dotted key":             "[[a]]\nb.c = 1\n[[a]]\n[a.b]\nd = 2\n",
	}
	for name, doc := range cases {
		tree, err := ParseMap([]byte(doc))
		if err != nil {
			t.Errorf("%s: %v", name, err)
			continue
		}
		elements := tree["a"].([]map[string]any)
		if len(elements) != 2 {
			t.Errorf("%s: len(a) = %d, want 2", name, len(elements))
		}
	}
	// Within one element the redefinition rules keep applying.
	for name, doc := range map[string]string{
		"header over dotted in one element": "[[a]]\nb.c = 1\n[a.b]\nd = 2\n",
		"table over nested array":           "[[a]]\n[[a.b]]\n[a.b]\nx = 1\n",
	} {
		if _, err := ParseMap([]byte(doc)); err == nil {
			t.Errorf("%s: expected an error, got none", name)
		}
	}
}

func TestRejectsSpecInvalid(t *testing.T) {
	cases := map[string]string{
		"single-digit hour":       "a = 2023-10-01T1:32:00Z\n",
		"inline duplicate key":    "a = { b = 1, b = 2 }\n",
		"inline dotted overwrite": "a = { b = 1, b.c = 2 }\n",
		"dotted over header":      "[a.b]\nx = 1\n[a]\nb.y = 2\n",
		"table over array":        "[[t]]\n[t]\n",
		"truncated datetime":      "a = 2026-01-02T\n",
		// "datetime no seconds" moved to the acceptance tests: TOML 1.1
		// makes the seconds optional.
	}
	for name, doc := range cases {
		if _, err := ParseMap([]byte(doc)); err == nil {
			t.Errorf("%s: expected an error", name)
		}
	}
}

func TestArrayOfTablesPerElementSubtable(t *testing.T) {
	tree, err := ParseMap([]byte(`
[[forms]]
name = "a"

[forms.smtp]
host = "h1"

[[forms]]
name = "b"

[forms.smtp]
host = "h2"
`))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	forms := tree["forms"].([]map[string]any)
	if len(forms) != 2 {
		t.Fatalf("len(forms) = %d", len(forms))
	}
	if h := forms[0]["smtp"].(map[string]any)["host"]; h != "h1" {
		t.Errorf("forms[0].smtp.host = %v", h)
	}
	if h := forms[1]["smtp"].(map[string]any)["host"]; h != "h2" {
		t.Errorf("forms[1].smtp.host = %v", h)
	}
}

// --- TOML 1.1 --------------------------------------------------------------

func TestParseAcceptsNoSecondsDatetimes(t *testing.T) {
	tree, err := ParseMap([]byte(`t = 13:37
dt = 1979-05-27T07:32
odt1 = 1979-05-27 07:32Z
odt2 = 1979-05-27 07:32-07:00
`))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	// A value written without seconds comes back without them: the seconds are
	// only written when the value carries them.
	if got := tree["t"].(LocalTime).String(); got != "13:37" {
		t.Errorf("t = %q, want %q", got, "13:37")
	}
	if got := tree["dt"].(LocalDateTime).String(); got != "1979-05-27T07:32" {
		t.Errorf("dt = %q, want %q", got, "1979-05-27T07:32")
	}
	if got := tree["odt1"].(OffsetDateTime).Format(time.RFC3339Nano); got != "1979-05-27T07:32:00Z" {
		t.Errorf("odt1 = %q", got)
	}
	if got := tree["odt2"].(OffsetDateTime).Format(time.RFC3339Nano); got != "1979-05-27T07:32:00-07:00" {
		t.Errorf("odt2 = %q", got)
	}
	// The fraction still requires the seconds it belongs to.
	if _, err := ParseMap([]byte("a = 07:32.5\n")); err == nil {
		t.Error("07:32.5: expected an error, got none")
	}
}

func TestParseAcceptsEscapeAndHexEscapes(t *testing.T) {
	tree, err := ParseMap([]byte(`esc = "\e"
hex = "\x20\x7f\xf8"
nul = "\x00"
multi = """\x68\x65"""
lit = '\x20'
`))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	if got := tree["esc"].(string); got != "\x1b" {
		t.Errorf("esc = %q, want the escape character", got)
	}
	if got := tree["hex"].(string); got != " \x7f\u00f8" {
		t.Errorf("hex = %q", got)
	}
	if got := tree["nul"].(string); got != "\x00" {
		t.Errorf("nul = %q", got)
	}
	if got := tree["multi"].(string); got != "he" {
		t.Errorf("multi = %q", got)
	}
	// A literal string carries the sequence verbatim.
	if got := tree["lit"].(string); got != `\x20` {
		t.Errorf("lit = %q, want the verbatim sequence", got)
	}
	// Two digits exactly; a short or non-hex escape is an error.
	for _, doc := range []string{`a = "\x4"`, `a = "\x"`, `a = "\xgg"`} {
		if _, err := ParseMap([]byte(doc)); err == nil {
			t.Errorf("%s: expected an error, got none", doc)
		}
	}
}

func TestParseAcceptsMultilineInlineTables(t *testing.T) {
	tree, err := ParseMap([]byte("tbl = {\n\thello = \"world\",\n\tarr = [1,\n\t\t2,\n\t],\n\tsub = {\n\t\tk = 1,\n\t},\n\tbare = 2}\n"))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	tbl := tree["tbl"].(map[string]any)
	if tbl["hello"] != "world" || tbl["bare"] != int64(2) {
		t.Fatalf("tbl = %#v", tbl)
	}
	if arr := tbl["arr"].([]any); len(arr) != 2 {
		t.Errorf("arr = %#v", tbl["arr"])
	}
	if sub := tbl["sub"].(map[string]any); sub["k"] != int64(1) {
		t.Errorf("sub = %#v", tbl["sub"])
	}
	// Comments inside the table, and a trailing comma at both depths.
	tree, err = ParseMap([]byte("m = { # one\n\t# two\n\ta = 1, # three\n\t# four\n}\n"))
	if err != nil {
		t.Fatalf("parse with comments: %v", err)
	}
	if m := tree["m"].(map[string]any); m["a"] != int64(1) {
		t.Errorf("m = %#v", m)
	}
	// The old single-line shapes keep working, with and without the comma.
	if _, err := ParseMap([]byte("a = { b = 1, c = 2 }\n")); err != nil {
		t.Errorf("single line: %v", err)
	}
	// Still rejected: two commas, a missing value, and an unclosed table.
	for name, doc := range map[string]string{
		"double comma":  "a = { b = 1,, c = 2 }\n",
		"missing value": "a = {\n\tb =\n}\n",
		"unterminated":  "a = { b = 1,\n",
	} {
		if _, err := ParseMap([]byte(doc)); err == nil {
			t.Errorf("%s: expected an error, got none", name)
		}
	}
}

func TestParseNestingLimit(t *testing.T) {
	// The parser is a recursive descent, so a document that nests without bound
	// is rejected instead of exhausting the stack.
	deep := func(n int) []byte {
		return []byte("v = " + strings.Repeat("[", n) + strings.Repeat("]", n) + "\n")
	}
	if _, err := ParseMap(deep(100)); err != nil {
		t.Fatalf("a document well inside the limit: %v", err)
	}
	_, err := ParseMap(deep(maxNestingDepth + 1))
	if err == nil {
		t.Fatal("expected a nesting error")
	}
	var se *SyntaxError
	if !errors.As(err, &se) {
		t.Fatalf("expected a *SyntaxError, got %T: %v", err, err)
	}
	if !strings.Contains(se.Msg, "nesting") {
		t.Errorf("Msg = %q, want it to name the nesting limit", se.Msg)
	}
}