// Copyright (c) 2026 Charles KWON OhJun (charleskwonohjun@gmail.com)
// All rights reserved.

package pgserver

import (
	"bytes"
	"strconv"
	"testing"

	"five/hbrt"
)

// TestEncodeText_Numeric pins the text-format encoding for the four
// numeric Five variants psql actually receives. Regressions here
// would surface as silently mis-formatted DataRow values that some
// clients render and others reject — easier to catch with a focused
// unit test than via a psql round-trip.
func TestEncodeText_Numeric(t *testing.T) {
	cases := []struct {
		name string
		v    hbrt.Value
		want []byte
	}{
		{"int-positive", hbrt.MakeInt(42), []byte("42")},
		{"int-negative", hbrt.MakeInt(-7), []byte("-7")},
		{"long", hbrt.MakeLong(9876543210), []byte("9876543210")},
		// MakeDouble's metadata: (value, len, dec) — dec=2 should
		// surface as "50000.00" not "50000".
		{"decimal-2dp", hbrt.MakeDouble(50000.0, 10, 2), []byte("50000.00")},
		{"decimal-fraction", hbrt.MakeDouble(42000.5, 10, 2), []byte("42000.50")},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			got := encodeText(tc.v)
			if !bytes.Equal(got, tc.want) {
				t.Errorf("encodeText: want %q, got %q", tc.want, got)
			}
		})
	}
}

// TestEncodeText_Strings covers the trivial case but also the NIL
// → nil-slice contract that DataRow uses to distinguish NULL from
// empty string ("" sends length=0; NIL sends length=-1).
func TestEncodeText_Strings(t *testing.T) {
	if got := encodeText(hbrt.MakeString("hello")); !bytes.Equal(got, []byte("hello")) {
		t.Errorf("string encode: got %q", got)
	}
	if got := encodeText(hbrt.MakeString("")); got == nil {
		t.Error("empty string must encode as []byte{}, not nil (NULL marker)")
	}
	if got := encodeText(hbrt.MakeNil()); got != nil {
		t.Errorf("NIL must encode as nil slice (PG NULL marker), got %q", got)
	}
	if got := encodeText(hbrt.MakeBool(true)); !bytes.Equal(got, []byte("t")) {
		t.Errorf("bool true: got %q", got)
	}
	if got := encodeText(hbrt.MakeBool(false)); !bytes.Equal(got, []byte("f")) {
		t.Errorf("bool false: got %q", got)
	}
}

// TestPgTypeFor verifies OID selection for the column-type
// detection path. Integer-shaped numerics that fit int32 must
// transit as INT4 so BI tools display them right-aligned with
// no decimal point.
func TestPgTypeFor(t *testing.T) {
	type ent struct {
		v       hbrt.Value
		wantOID uint32
	}
	for i, tc := range []ent{
		{hbrt.MakeInt(0), oidInt4},
		{hbrt.MakeInt(2147483647), oidInt4},
		{hbrt.MakeLong(9999999999), oidInt8},
		{hbrt.MakeDouble(1.5, 10, 2), oidNumeric},
		{hbrt.MakeString("x"), oidText},
		{hbrt.MakeBool(true), oidBool},
		{hbrt.MakeNil(), oidText}, // fallback when no sample
	} {
		oid, _ := pgTypeFor(tc.v)
		if oid != tc.wantOID {
			t.Errorf("case %d: want oid %d, got %d", i, tc.wantOID, oid)
		}
	}
}

// TestSqlStateFor verifies the FiveSql2-error-code → SQLSTATE map.
// Drivers dispatch on the leading two chars (class code), so the
// table needs to match the canonical PG layout for libpq-style
// exception handling to work.
func TestSqlStateFor(t *testing.T) {
	want := map[int]string{
		1:   "42601",
		2:   "42P01",
		3:   "42703",
		8:   "25P02",
		99:  "XX000",
	}
	for code, expect := range want {
		got := sqlStateFor(code)
		if got != expect {
			t.Errorf("sqlStateFor(%d) = %q, want %q", code, got, expect)
		}
	}
}

// TestCommandTagFor pins the CommandComplete tag verbs. Tagged
// rows (n) come in Phase 3; for v1.0 we always emit "VERB 0" so
// psql-style row-count display works (it prints "(0 행)" but
// doesn't error out).
func TestCommandTagFor(t *testing.T) {
	cases := []struct{ sql, want string }{
		{"SELECT * FROM x", "SELECT 0"},
		{"  select 1", "SELECT 0"},
		{"INSERT INTO x VALUES (1)", "INSERT 0"},
		{"UPDATE x SET a=1", "UPDATE 0"},
		{"DELETE FROM x", "DELETE 0"},
		{"BEGIN", "BEGIN"},
		{"COMMIT", "COMMIT"},
		{"CREATE TABLE foo (x INT)", "CREATE"},
	}
	for _, c := range cases {
		if got := commandTagFor(c.sql); got != c.want {
			t.Errorf("commandTagFor(%q) = %q, want %q", c.sql, got, c.want)
		}
	}
	_ = strconv.Itoa // keep import; will be used in Phase 3 with row counts
}