package gudusoft.gsqlparser.resolver;

import gudusoft.gsqlparser.TBaseType;
import gudusoft.gsqlparser.TLog;
import gudusoft.gsqlparser.TStatementList;
import gudusoft.gsqlparser.compiler.TContext;

/**
 * TSQLResolver handles all semantic analysis and resolution steps for SQL statements.
 * This class consolidates various resolution algorithms to provide a clear, maintainable
 * structure for SQL semantic analysis.
 *
 * 涉及的重要 类有:
 * @see gudusoft.gsqlparser.TAttributeNode
 */
public class TSQLResolver {
    private final TContext globalContext;
    private final TStatementList sqlStatements;
   // private final TLog logger;
   private int iterationCount;
   private int newColumnsLastIteration;

    /**
     * Creates a new SQL resolver instance.
     * 
     * @param context The global context containing SQL environment and scope information
     * @param statements List of SQL statements to analyze
     */
    public TSQLResolver(TContext context, TStatementList statements) {
        this.globalContext = context;
        this.sqlStatements = statements;
       // this.logger = new TLog();
       this.iterationCount = 0;
       this.newColumnsLastIteration = 0;
    }

    /**
     * Performs complete semantic analysis of SQL statements.
     * Executes all resolution steps in the correct order.
     * 
     * @return true if resolution completes successfully, false if errors occurred
     */
    public boolean resolve() {
        TLog.clearLogs();
        if (!TBaseType.DUMP_RESOLVER_LOG_TO_CONSOLE){
            TLog.disableLog();
        }else{
            TLog.enableAllLevelLog();
        }

        try {
            collectMetadata();
            resolveDatabaseObjects();

            do {
                iterationCount++;
                newColumnsLastIteration = 0;

                if (TBaseType.DUMP_RESOLVER_LOG_TO_CONSOLE){
                    TBaseType.log(String.format("Starting resolve relationships in iteration %d", iterationCount), TLog.DEBUG);
                }
                resolveRelationships();  // 更新表属性
                if (TBaseType.DUMP_RESOLVER_LOG_TO_CONSOLE){
                    TBaseType.log(String.format("Starting expand star columns in iteration %d", iterationCount), TLog.DEBUG);
                }
                expandStarColumns();     // 展开星号列
                if (TBaseType.DUMP_RESOLVER_LOG_TO_CONSOLE){
                    TBaseType.log(String.format("Starting resolve attributes in iteration %d", iterationCount), TLog.DEBUG);
                }
                resolveAttributes();     // 先收集列引用
                if (TBaseType.DUMP_RESOLVER_LOG_TO_CONSOLE){
                    TBaseType.log(String.format("Starting resolve star columns in iteration %d", iterationCount), TLog.DEBUG);
                }

                resolveStarColumns();    // 推送星号列

                if (TBaseType.DUMP_RESOLVER_LOG_TO_CONSOLE){
                    TBaseType.log(String.format("Iteration %d: %d new columns inferred", iterationCount, newColumnsLastIteration), TLog.DEBUG);
                }
            } while (newColumnsLastIteration > 0 && iterationCount < 10);
            
        } catch (Exception e) {
            TBaseType.log("Exception raised in TSQLResolver.resolve(): " + e.getMessage(), TLog.ERROR);
            throw e;
        }


       if (TBaseType.DUMP_RESOLVER_LOG_TO_CONSOLE){
           TBaseType.dumpLogs(false);
       }
        return true;
    }

    /**
     * Collects metadata from DDL statements like CREATE TABLE, CREATE VIEW, etc.
     * Uses TMetadataCollector to build the metadata repository.
     */
    private void collectMetadata() {
        TMetadataCollector collector = new TMetadataCollector(sqlStatements, globalContext);
        collector.collect();
    }

    /**
     * Resolves database objects by linking references to their definitions.
     * Handles table names, view names, and other database objects.
     */
    private void resolveDatabaseObjects() {
        TDatabaseObjectResolver resolver = new TDatabaseObjectResolver(sqlStatements,globalContext);
        resolver.resolve();
    }

    /**
     * Resolves relationships between database objects.
     * This includes JOIN conditions, foreign key relationships, etc.
     */
    private void resolveRelationships() {
        new TRelationResolver(sqlStatements, globalContext, this).resolve();
    }

    /**
     * Resolves relationships between database objects.
     * This includes JOIN conditions, foreign key relationships, etc.
     */
    private void resolveRelationships2() {
        TRelationResolver2 resolver = new TRelationResolver2(sqlStatements,globalContext);
        resolver.resolve();
    }

    /**
     * Expands star columns (*) and processes subqueries.
     * Converts * to explicit column lists and handles subquery resolution.
     */
    private void expandStarColumns() {
        new TStarColumnExpander(sqlStatements, globalContext,this).resolve();
    }

    /**
     * Resolves column attributes including data types, constraints, etc.
     */
    private void resolveAttributes() {
        new TAttributeResolver(sqlStatements, globalContext, this).resolve();
    }

    /**
     * Performs final resolution of star columns after all other resolutions.
     * This handles any remaining star column cases that depend on previous steps.
     */
    private void resolveStarColumns() {
        TStarColumnPushDownResolver starColumnPushDownResolver = new TStarColumnPushDownResolver(sqlStatements,globalContext);
        starColumnPushDownResolver.resolve();
    }

    public void reportNewColumns(int count) {
        newColumnsLastIteration += count;
    }    

    /**
     * Gets the log containing resolution messages and errors.
     * 
     * @return The resolution log
     */
    // public TLog getLog() {
    //     return logger;
    // }
}