#include "sqliteInt.h"
#include "unity.h"

#include <string.h>
#include <stdio.h>

/* Helper: execute SQL and assert success */
static void execSQL(sqlite3 *db, const char *zSql){
  char *zErr = 0;
  int rc = sqlite3_exec(db, zSql, 0, 0, &zErr);
  if( rc!=SQLITE_OK ){
    fprintf(stderr, "SQL error (%d): %s while running: %s\n", rc, zErr?zErr:"(null)", zSql);
  }
  TEST_ASSERT_EQUAL_INT_MESSAGE(SQLITE_OK, rc, "sqlite3_exec failed");
  if( zErr ) sqlite3_free(zErr);
}

/* Helper: create a SrcList for a single table name */
static SrcList *makeSrcList(sqlite3 *db, const char *zName){
  Token tName;
  tName.z = zName;
  tName.n = (int)strlen(zName);
  return sqlite3SrcListAppend(db, 0, &tName, 0);
}

/* Helper: initialize a Parse object */
static void initParse(sqlite3 *db, Parse *p){
  memset(p, 0, sizeof(*p));
  p->db = db;
}

/* Helper: free Parse resources left after calling the target function */
static void cleanupParse(sqlite3 *db, Parse *p){
  if( p->zErrMsg ){
    sqlite3DbFree(db, p->zErrMsg);
    p->zErrMsg = 0;
  }
  if( p->pVdbe ){
    sqlite3VdbeDelete(p->pVdbe);
    p->pVdbe = 0;
  }
}

void setUp(void) {
  /* No global setup */
}

void tearDown(void) {
  /* No global teardown */
}

/* Test: dropping a non-existent column reports an error */
void test_sqlite3AlterDropColumn_no_such_column(void){
  sqlite3 *db = 0;
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, sqlite3_open(":memory:", &db));

  execSQL(db, "CREATE TABLE t1(a, b);");

  Parse p;
  initParse(db, &p);
  SrcList *pSrc = makeSrcList(db, "t1");

  Token tCol;
  tCol.z = "c";
  tCol.n = 1;

  sqlite3BtreeEnterAll(db);
  sqlite3AlterDropColumn(&p, pSrc, &tCol);
  sqlite3BtreeLeaveAll(db);

  TEST_ASSERT_TRUE_MESSAGE(p.nErr>0, "Expected error for non-existent column");
  TEST_ASSERT_NOT_NULL(p.zErrMsg);
  TEST_ASSERT_NOT_EQUAL(-1, (int)sqlite3StrLike("no such column:%", p.zErrMsg, 0)); /* rough check */
  /* Also check substring for robustness */
  TEST_ASSERT_NOT_EQUAL(NULL, strstr(p.zErrMsg, "no such column"));

  cleanupParse(db, &p);
  sqlite3_close(db);
}

/* Test: cannot drop PRIMARY KEY column */
void test_sqlite3AlterDropColumn_drop_primary_key_column(void){
  sqlite3 *db = 0;
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, sqlite3_open(":memory:", &db));

  execSQL(db, "CREATE TABLE tpk(a INTEGER PRIMARY KEY, b);");

  Parse p;
  initParse(db, &p);
  SrcList *pSrc = makeSrcList(db, "tpk");

  Token tCol;
  tCol.z = "a";
  tCol.n = 1;

  sqlite3BtreeEnterAll(db);
  sqlite3AlterDropColumn(&p, pSrc, &tCol);
  sqlite3BtreeLeaveAll(db);

  TEST_ASSERT_TRUE_MESSAGE(p.nErr>0, "Expected error dropping PRIMARY KEY column");
  TEST_ASSERT_NOT_NULL(p.zErrMsg);
  TEST_ASSERT_NOT_EQUAL(NULL, strstr(p.zErrMsg, "PRIMARY KEY"));

  cleanupParse(db, &p);
  sqlite3_close(db);
}

/* Test: cannot drop a column with a column-level UNIQUE constraint */
void test_sqlite3AlterDropColumn_drop_unique_column(void){
  sqlite3 *db = 0;
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, sqlite3_open(":memory:", &db));

  /* Column-level UNIQUE to set COLFLAG_UNIQUE */
  execSQL(db, "CREATE TABLE tu(a UNIQUE, b);");

  Parse p;
  initParse(db, &p);
  SrcList *pSrc = makeSrcList(db, "tu");

  Token tCol;
  tCol.z = "a";
  tCol.n = 1;

  sqlite3BtreeEnterAll(db);
  sqlite3AlterDropColumn(&p, pSrc, &tCol);
  sqlite3BtreeLeaveAll(db);

  TEST_ASSERT_TRUE_MESSAGE(p.nErr>0, "Expected error dropping UNIQUE column");
  TEST_ASSERT_NOT_NULL(p.zErrMsg);
  TEST_ASSERT_NOT_EQUAL(NULL, strstr(p.zErrMsg, "UNIQUE"));

  cleanupParse(db, &p);
  sqlite3_close(db);
}

/* Test: cannot drop the last remaining column of a table */
void test_sqlite3AlterDropColumn_drop_only_remaining_column(void){
  sqlite3 *db = 0;
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, sqlite3_open(":memory:", &db));

  execSQL(db, "CREATE TABLE t1col(a);");

  Parse p;
  initParse(db, &p);
  SrcList *pSrc = makeSrcList(db, "t1col");

  Token tCol;
  tCol.z = "a";
  tCol.n = 1;

  sqlite3BtreeEnterAll(db);
  sqlite3AlterDropColumn(&p, pSrc, &tCol);
  sqlite3BtreeLeaveAll(db);

  TEST_ASSERT_TRUE_MESSAGE(p.nErr>0, "Expected error dropping the only column");
  TEST_ASSERT_NOT_NULL(p.zErrMsg);
  TEST_ASSERT_NOT_EQUAL(NULL, strstr(p.zErrMsg, "no other columns exist"));

  cleanupParse(db, &p);
  sqlite3_close(db);
}

/* Test: cannot drop a column from a view */
void test_sqlite3AlterDropColumn_on_view(void){
  sqlite3 *db = 0;
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, sqlite3_open(":memory:", &db));

  execSQL(db, "CREATE VIEW v1 AS SELECT 1 AS a, 2 AS b;");

  Parse p;
  initParse(db, &p);
  SrcList *pSrc = makeSrcList(db, "v1");

  Token tCol;
  tCol.z = "a";
  tCol.n = 1;

  sqlite3BtreeEnterAll(db);
  sqlite3AlterDropColumn(&p, pSrc, &tCol);
  sqlite3BtreeLeaveAll(db);

  TEST_ASSERT_TRUE_MESSAGE(p.nErr>0, "Expected error dropping column from view");
  TEST_ASSERT_NOT_NULL(p.zErrMsg);
  TEST_ASSERT_NOT_EQUAL(NULL, strstr(p.zErrMsg, "drop column from view"));

  cleanupParse(db, &p);
  sqlite3_close(db);
}

/* Test: successful generation for dropping a regular column from a table */
void test_sqlite3AlterDropColumn_success_generates_vdbe(void){
  sqlite3 *db = 0;
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, sqlite3_open(":memory:", &db));

  execSQL(db, "CREATE TABLE tgood(a, b, c);");
  execSQL(db, "INSERT INTO tgood VALUES(1,2,3);");

  Parse p;
  initParse(db, &p);
  SrcList *pSrc = makeSrcList(db, "tgood");

  Token tCol;
  tCol.z = "b";
  tCol.n = 1;

  sqlite3BtreeEnterAll(db);
  sqlite3AlterDropColumn(&p, pSrc, &tCol);
  sqlite3BtreeLeaveAll(db);

  TEST_ASSERT_EQUAL_INT_MESSAGE(0, p.nErr, "Unexpected error during valid drop column codegen");
  TEST_ASSERT_NOT_NULL_MESSAGE(p.pVdbe, "Expected VDBE code to be generated");
  TEST_ASSERT_TRUE_MESSAGE(p.nMem>0 || p.nTab>0, "Expected some registers/cursors allocated");

  cleanupParse(db, &p);
  sqlite3_close(db);
}

int main(void){
  UNITY_BEGIN();
  RUN_TEST(test_sqlite3AlterDropColumn_no_such_column);
  RUN_TEST(test_sqlite3AlterDropColumn_drop_primary_key_column);
  RUN_TEST(test_sqlite3AlterDropColumn_drop_unique_column);
  RUN_TEST(test_sqlite3AlterDropColumn_drop_only_remaining_column);
  RUN_TEST(test_sqlite3AlterDropColumn_on_view);
  RUN_TEST(test_sqlite3AlterDropColumn_success_generates_vdbe);
  return UNITY_END();
}