package gudusoft.gsqlparser.resolver2.expansion;

import gudusoft.gsqlparser.nodes.TResultColumn;
import gudusoft.gsqlparser.resolver2.model.ColumnSource;

/**
 * Represents a column expanded from a star (*) column.
 *
 * <p>When SELECT * is expanded, each column from the source tables
 * becomes an ExpandedColumn. This class tracks:
 * - The column name
 * - The original star column it came from
 * - The source (which table/namespace)
 * - Whether to include table qualifier
 *
 * <p>Example:
 * <pre>
 * SELECT * FROM employees
 * -- Expands to:
 * ExpandedColumn("id", employees.id, *, true)
 * ExpandedColumn("name", employees.name, *, true)
 * ExpandedColumn("salary", employees.salary, *, true)
 * </pre>
 */
public class ExpandedColumn {

    /** The column name */
    private final String columnName;

    /** The source of this column (which table/namespace) */
    private final ColumnSource columnSource;

    /** The original star column this was expanded from */
    private final TResultColumn originalStarColumn;

    /** The table qualifier (if qualified star like t1.*) */
    private final String tableQualifier;

    /** Whether to include table qualifier in the expanded name */
    private final boolean includeQualifier;

    /**
     * Create an expanded column from an unqualified star.
     *
     * @param columnName the column name
     * @param columnSource the column source
     * @param originalStarColumn the original star column
     * @param includeQualifier whether to include table qualifier
     */
    public ExpandedColumn(
            String columnName,
            ColumnSource columnSource,
            TResultColumn originalStarColumn,
            boolean includeQualifier) {
        this.columnName = columnName;
        this.columnSource = columnSource;
        this.originalStarColumn = originalStarColumn;
        this.tableQualifier = null;
        this.includeQualifier = includeQualifier;
    }

    /**
     * Create an expanded column from a qualified star (e.g., t1.*).
     *
     * @param columnName the column name
     * @param columnSource the column source
     * @param originalStarColumn the original star column
     * @param tableQualifier the table qualifier (e.g., "t1")
     * @param includeQualifier whether to include table qualifier
     */
    public ExpandedColumn(
            String columnName,
            ColumnSource columnSource,
            TResultColumn originalStarColumn,
            String tableQualifier,
            boolean includeQualifier) {
        this.columnName = columnName;
        this.columnSource = columnSource;
        this.originalStarColumn = originalStarColumn;
        this.tableQualifier = tableQualifier;
        this.includeQualifier = includeQualifier;
    }

    public String getColumnName() {
        return columnName;
    }

    public ColumnSource getColumnSource() {
        return columnSource;
    }

    public TResultColumn getOriginalStarColumn() {
        return originalStarColumn;
    }

    public String getTableQualifier() {
        return tableQualifier;
    }

    public boolean isQualified() {
        return tableQualifier != null;
    }

    /**
     * Get the fully qualified column name (e.g., "t1.id").
     *
     * @return qualified name if qualifier is set, otherwise just column name
     */
    public String getQualifiedName() {
        if (includeQualifier && tableQualifier != null && !tableQualifier.isEmpty()) {
            return tableQualifier + "." + columnName;
        } else if (includeQualifier && columnSource != null &&
                   columnSource.getFinalTable() != null &&
                   !columnSource.isColumnAlias() &&
                   columnSource.getFinalColumnName() == null) {
            String tableName = columnSource.getFinalTable().getAliasName();
            if (tableName == null || tableName.isEmpty()) {
                tableName = columnSource.getFinalTable().getName();
            }
            if (tableName != null && !tableName.isEmpty()) {
                return tableName + "." + columnName;
            }
            // Try getting table name from TTable.getTableName()
            gudusoft.gsqlparser.nodes.TObjectName tableNameObj = columnSource.getFinalTable().getTableName();
            if (tableNameObj != null) {
                String tableStr = tableNameObj.getTableString();
                if (tableStr != null && !tableStr.isEmpty()) {
                    return tableStr + "." + columnName;
                }
            }
        }
        return columnName;
    }

    /**
     * Get the column name without qualifier.
     *
     * @return unqualified column name
     */
    public String getUnqualifiedName() {
        return columnName;
    }

    /**
     * Get the confidence score for this expanded column.
     *
     * @return confidence [0.0, 1.0], or 1.0 if no source available
     */
    public double getConfidence() {
        return columnSource != null ? columnSource.getConfidence() : 1.0;
    }

    @Override
    public String toString() {
        return getQualifiedName();
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (!(obj instanceof ExpandedColumn)) return false;
        ExpandedColumn other = (ExpandedColumn) obj;
        return getQualifiedName().equals(other.getQualifiedName());
    }

    @Override
    public int hashCode() {
        return getQualifiedName().hashCode();
    }
}