package pgsql

import (
	"bytes"
	"strings"
	"testing"

	"git.warky.dev/wdevs/relspecgo/pkg/models"
	"git.warky.dev/wdevs/relspecgo/pkg/writers"
)

func serialTestTable(colType string, def interface{}) *models.Table {
	table := models.InitTable("login_event", "identity")
	id := models.InitColumn("id_login_event", "login_event", "identity")
	id.Type = colType
	id.IsPrimaryKey = true
	id.Default = def
	table.Columns["id_login_event"] = id
	return table
}

func serialTestDB(table *models.Table) *models.Database {
	db := models.InitDatabase("testdb")
	schema := models.InitSchema("identity")
	schema.Tables = append(schema.Tables, table)
	db.Schemas = append(db.Schemas, schema)
	return db
}

func TestSequences_FollowPrimaryKeyDefault(t *testing.T) {
	tests := []struct {
		name        string
		table       *models.Table
		wantContain []string
		wantAbsent  []string
	}{
		{
			name:  "nextval default uses its own sequence",
			table: serialTestTable("bigint", "nextval('identity.login_event_id_login_event_seq'::regclass)"),
			wantContain: []string{
				"login_event_id_login_event_seq",
				"setval(",
			},
			wantAbsent: []string{"identity_login_event_id_login_event"},
		},
		{
			name:       "no default creates no sequence",
			table:      serialTestTable("bigint", nil),
			wantAbsent: []string{"CREATE SEQUENCE", "setval("},
		},
		{
			name:       "bigserial without default creates no extra sequence",
			table:      serialTestTable("bigserial", nil),
			wantAbsent: []string{"CREATE SEQUENCE", "setval(", "identity_login_event_id_login_event"},
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			var buf bytes.Buffer
			w := NewWriter(&writers.WriterOptions{})
			w.writer = &buf
			if err := w.WriteDatabase(serialTestDB(tt.table)); err != nil {
				t.Fatalf("WriteDatabase failed: %v", err)
			}
			full := buf.String()

			stmts, err := w.GenerateDatabaseStatements(serialTestDB(tt.table))
			if err != nil {
				t.Fatalf("GenerateDatabaseStatements failed: %v", err)
			}
			for label, out := range map[string]string{"WriteDatabase": full, "GenerateDatabaseStatements": diffJoin(stmts)} {
				for _, s := range tt.wantContain {
					if !strings.Contains(out, s) {
						t.Errorf("%s: missing %q\n%s", label, s, out)
					}
				}
				for _, s := range tt.wantAbsent {
					if strings.Contains(out, s) {
						t.Errorf("%s: unexpected %q\n%s", label, s, out)
					}
				}
			}
		})
	}
}

func TestSetSequenceValue_OnlyMovesForwardPastData(t *testing.T) {
	w := NewWriter(&writers.WriterOptions{})
	table := serialTestTable("bigint", "nextval('identity.login_event_id_login_event_seq'::regclass)")
	stmt, err := w.primaryKeySetvalStatement(serialTestDB(table).Schemas[0], table)
	if err != nil {
		t.Fatal(err)
	}
	for _, want := range []string{"MAX(", "is_called", "m_cnt > m_next", ", m_cnt, false)"} {
		if !strings.Contains(stmt, want) {
			t.Errorf("setval statement missing %q:\n%s", want, stmt)
		}
	}
}

func TestDiffStatements_ExistingTableNewSequenceIsSetPastData(t *testing.T) {
	def := "nextval('identity.login_event_id_login_event_seq'::regclass)"
	model := serialTestDB(serialTestTable("bigint", def))
	current := serialTestDB(serialTestTable("bigint", nil))

	w := NewWriter(&writers.WriterOptions{})
	stmts, err := w.diffStatements(model, current)
	if err != nil {
		t.Fatalf("diffStatements failed: %v", err)
	}
	out := diffJoin(stmts)
	seqIdx := strings.Index(out, "CREATE SEQUENCE IF NOT EXISTS identity.login_event_id_login_event_seq")
	setvalIdx := strings.Index(out, "setval(")
	if seqIdx < 0 || setvalIdx < 0 || seqIdx > setvalIdx {
		t.Fatalf("expected sequence creation before setval, got:\n%s", out)
	}

	// Sequence already present in the database: nothing to create or move.
	current.Schemas[0].Sequences = append(current.Schemas[0].Sequences,
		models.InitSequence("login_event_id_login_event_seq", "identity"))
	stmts, err = w.diffStatements(model, current)
	if err != nil {
		t.Fatalf("diffStatements failed: %v", err)
	}
	if strings.Contains(diffJoin(stmts), "setval(") || strings.Contains(diffJoin(stmts), "CREATE SEQUENCE") {
		t.Fatalf("existing sequence must be left alone:\n%s", diffJoin(stmts))
	}
}

func TestSerialWithoutDefault_DoesNotDropExistingDefault(t *testing.T) {
	def := "nextval('identity.login_event_id_login_event_seq'::regclass)"
	model := serialTestDB(serialTestTable("bigserial", nil))
	current := serialTestDB(serialTestTable("bigserial", def))

	w := NewWriter(&writers.WriterOptions{})
	stmts, err := w.diffStatements(model, current)
	if err != nil {
		t.Fatalf("diffStatements failed: %v", err)
	}
	if strings.Contains(strings.ToUpper(diffJoin(stmts)), "DROP DEFAULT") {
		t.Fatalf("serial default must not be dropped:\n%s", diffJoin(stmts))
	}

	alter, err := w.GenerateAlterColumnDefaultStatements(model.Schemas[0])
	if err != nil {
		t.Fatal(err)
	}
	if strings.Contains(strings.ToUpper(diffJoin(alter)), "DROP DEFAULT") {
		t.Fatalf("full-DDL path must not drop serial default:\n%s", diffJoin(alter))
	}

	// A plain bigint with no model default still has its default dropped.
	model = serialTestDB(serialTestTable("bigint", nil))
	current = serialTestDB(serialTestTable("bigint", def))
	stmts, err = w.diffStatements(model, current)
	if err != nil {
		t.Fatal(err)
	}
	if !strings.Contains(strings.ToUpper(diffJoin(stmts)), "DROP DEFAULT") {
		t.Fatalf("non-serial default removal should still be emitted:\n%s", diffJoin(stmts))
	}
}