package gudusoft.gsqlparser.resolver2.model;

import gudusoft.gsqlparser.TSourceToken;
import gudusoft.gsqlparser.nodes.TObjectName;

/**
 * Column reference record - preserves original AST node information for traceability.
 *
 * <p>When multiple syntactically different identifiers refer to the same semantic column
 * (e.g., "Column1" and column1 in Oracle), this class allows tracing back from
 * the normalized column name to all original occurrences in the SQL text.</p>
 *
 * <p>Example: For SQL {@code SELECT "Column1", column1 FROM dual}:</p>
 * <ul>
 *   <li>Both references resolve to the same column COLUMN1</li>
 *   <li>Each creates a separate ColumnReference with its original text and position</li>
 *   <li>The ColumnSourceWithReferences holds both references</li>
 * </ul>
 *
 * @since 3.1.0.9
 */
public class ColumnReference {

    /** Original AST node */
    private final TObjectName objectName;

    /** Original text as it appears in SQL (e.g., "Column1" or column1) */
    private final String originalText;

    /** Start offset in SQL text */
    private final int startOffset;

    /** End offset in SQL text */
    private final int endOffset;

    /** Line number (1-based) */
    private final int lineNumber;

    /** Column number (1-based) */
    private final int columnNumber;

    /**
     * Create a column reference from a TObjectName AST node.
     *
     * @param objectName the original AST node
     */
    public ColumnReference(TObjectName objectName) {
        this.objectName = objectName;
        this.originalText = objectName != null ? objectName.toString() : null;

        // Extract position information from token
        if (objectName != null && objectName.getStartToken() != null) {
            TSourceToken startToken = objectName.getStartToken();
            this.startOffset = (int) startToken.offset;
            this.lineNumber = (int) startToken.lineNo;
            this.columnNumber = (int) startToken.columnNo;

            TSourceToken endToken = objectName.getEndToken();
            this.endOffset = endToken != null ? (int) (endToken.offset + endToken.astext.length()) : startOffset;
        } else {
            this.startOffset = -1;
            this.endOffset = -1;
            this.lineNumber = -1;
            this.columnNumber = -1;
        }
    }

    /**
     * Create a column reference with explicit values (for testing or special cases).
     *
     * @param objectName the original AST node (may be null)
     * @param originalText the original text
     * @param startOffset start offset
     * @param endOffset end offset
     * @param lineNumber line number
     * @param columnNumber column number
     */
    public ColumnReference(TObjectName objectName, String originalText,
                          int startOffset, int endOffset,
                          int lineNumber, int columnNumber) {
        this.objectName = objectName;
        this.originalText = originalText;
        this.startOffset = startOffset;
        this.endOffset = endOffset;
        this.lineNumber = lineNumber;
        this.columnNumber = columnNumber;
    }

    /**
     * Get the original AST node.
     *
     * @return the TObjectName node, or null if not available
     */
    public TObjectName getObjectName() {
        return objectName;
    }

    /**
     * Get the original text as it appears in SQL.
     *
     * @return original text (e.g., "Column1" with quotes, or column1 without)
     */
    public String getOriginalText() {
        return originalText;
    }

    /**
     * Get the start offset in the SQL text.
     *
     * @return start offset (0-based), or -1 if not available
     */
    public int getStartOffset() {
        return startOffset;
    }

    /**
     * Get the end offset in the SQL text.
     *
     * @return end offset (0-based, exclusive), or -1 if not available
     */
    public int getEndOffset() {
        return endOffset;
    }

    /**
     * Get the line number.
     *
     * @return line number (1-based), or -1 if not available
     */
    public int getLineNumber() {
        return lineNumber;
    }

    /**
     * Get the column number.
     *
     * @return column number (1-based), or -1 if not available
     */
    public int getColumnNumber() {
        return columnNumber;
    }

    /**
     * Check if position information is available.
     *
     * @return true if position information is valid
     */
    public boolean hasPositionInfo() {
        return startOffset >= 0 && lineNumber >= 0;
    }

    @Override
    public String toString() {
        if (hasPositionInfo()) {
            return String.format("%s @ line %d, col %d (offset %d-%d)",
                originalText, lineNumber, columnNumber, startOffset, endOffset);
        }
        return originalText != null ? originalText : "<null>";
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        ColumnReference that = (ColumnReference) o;
        // Two references are equal if they point to the same location
        return startOffset == that.startOffset &&
               lineNumber == that.lineNumber &&
               columnNumber == that.columnNumber;
    }

    @Override
    public int hashCode() {
        int result = startOffset;
        result = 31 * result + lineNumber;
        result = 31 * result + columnNumber;
        return result;
    }
}