package db

import (
	"context"
	"database/sql"
	"fmt"
	"net/url"

	ora "github.com/sijms/go-ora/v2"
)

func openOracle(c ConnReq) (*sql.DB, error) {
	host := c.Host
	if host == "" {
		host = "127.0.0.1"
	}
	port := c.Port
	if port == 0 {
		port = 1521
	}
	user := c.User
	if user == "" {
		user = "system"
	}
	service := c.Service
	if service == "" {
		if c.Database != "" {
			service = c.Database
		} else {
			service = "XEPDB1"
		}
	}
	dsn := fmt.Sprintf("oracle://%s:%s@%s:%d/%s", url.PathEscape(user), url.PathEscape(c.Password), host, port, service)
	mode := EffectiveSSLMode(c)
	if mode != "disable" {
		q := url.Values{}
		q.Set("SSL", "true")
		if mode == "skip-verify" {
			q.Set("SSL VERIFY", "false")
		} else {
			q.Set("SSL VERIFY", "true")
		}
		dsn = dsn + "?" + q.Encode()
	}

	tlsCfg, err := tlsConfigFrom(c)
	if err != nil {
		return nil, err
	}
	if tlsCfg != nil {
		connector := ora.NewConnector(dsn)
		oc, ok := connector.(*ora.OracleConnector)
		if !ok {
			return nil, fmt.Errorf("oracle: connector 类型异常")
		}
		oc.WithTLSConfig(tlsCfg)
		return sql.OpenDB(oc), nil
	}
	return sql.Open("oracle", dsn)
}

func listDatabasesOracle(ctx context.Context, db *sql.DB) ([]string, error) {
	// 返回当前用户可见 schema
	rows, err := db.QueryContext(ctx, `SELECT username FROM all_users ORDER BY username`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []string
	for rows.Next() {
		var name string
		if err := rows.Scan(&name); err != nil {
			return nil, err
		}
		out = append(out, name)
	}
	return out, rows.Err()
}

func listTablesOracle(ctx context.Context, db *sql.DB, schema string) ([]string, error) {
	var (
		rows *sql.Rows
		err  error
	)
	if schema == "" {
		rows, err = db.QueryContext(ctx, `SELECT table_name FROM user_tables ORDER BY table_name`)
	} else {
		rows, err = db.QueryContext(ctx, `SELECT table_name FROM all_tables WHERE owner = UPPER(:1) ORDER BY table_name`, schema)
	}
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []string
	for rows.Next() {
		var name string
		if err := rows.Scan(&name); err != nil {
			return nil, err
		}
		out = append(out, name)
	}
	return out, rows.Err()
}

func listColumnsOracle(ctx context.Context, dbh *sql.DB, schema, table string) ([]ColumnInfo, error) {
	owner, t := splitSchemaTable(table)
	if owner == "" {
		owner = schema
	}
	var (
		rows *sql.Rows
		err  error
	)
	// 关联约束元数据补主键标记(命中则 Key='PRI');沿用既有 UPPER() 绑定约定
	if owner == "" {
		rows, err = dbh.QueryContext(ctx, `
			SELECT c.column_name, c.data_type, c.nullable, c.data_default,
				CASE WHEN acc.column_name IS NOT NULL THEN 'PRI' ELSE '' END
			FROM user_tab_columns c
			LEFT JOIN user_constraints ac ON ac.table_name = UPPER(:1) AND ac.constraint_type = 'P'
			LEFT JOIN user_cons_columns acc ON acc.constraint_name = ac.constraint_name
				AND acc.table_name = ac.table_name AND acc.column_name = c.column_name
			WHERE c.table_name = UPPER(:2)
			ORDER BY c.column_id`, t, t)
	} else {
		rows, err = dbh.QueryContext(ctx, `
			SELECT c.column_name, c.data_type, c.nullable, c.data_default,
				CASE WHEN acc.column_name IS NOT NULL THEN 'PRI' ELSE '' END
			FROM all_tab_columns c
			LEFT JOIN all_constraints ac ON ac.owner = UPPER(:1) AND ac.table_name = UPPER(:2) AND ac.constraint_type = 'P'
			LEFT JOIN all_cons_columns acc ON acc.owner = ac.owner AND acc.constraint_name = ac.constraint_name
				AND acc.column_name = c.column_name
			WHERE c.owner = UPPER(:3) AND c.table_name = UPPER(:4)
			ORDER BY c.column_id`, owner, t, owner, t)
	}
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []ColumnInfo
	for rows.Next() {
		var name, typ, nullable, key string
		var def sql.NullString
		if err := rows.Scan(&name, &typ, &nullable, &def, &key); err != nil {
			return nil, err
		}
		col := ColumnInfo{Name: name, Type: typ, Nullable: nullable == "Y", Key: key}
		if def.Valid {
			col.Default = def.String
		}
		out = append(out, col)
	}
	if out == nil {
		out = []ColumnInfo{}
	}
	return out, rows.Err()
}