#include "sqliteInt.h"
#include "unity.h"
#include <string.h>
#include <stdio.h>

/* Global db handle for tests */
static sqlite3 *gDb = NULL;

/* Helpers to create minimal Parse/pNewTable environment needed by sqlite3AlterFinishAddColumn */

static void init_db_and_base_table(const char *zCreate){
  int rc;
  rc = sqlite3_open(":memory:", &gDb);
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, rc);
  rc = sqlite3_exec(gDb, zCreate, 0, 0, 0);
  TEST_ASSERT_EQUAL_INT(SQLITE_OK, rc);
}

/* Allocate a minimal Table used as pParse->pNewTable for ALTER ADD COLUMN. */
static Table *allocNewAlterTable(sqlite3 *db, const char *zTabName){
  Table *pNew = (Table*)sqlite3DbMallocZero(db, sizeof(Table));
  TEST_ASSERT_NOT_NULL(pNew);
  /* Ordinary table with schema = main */
  pNew->pSchema = db->aDb[0].pSchema;
  /* pNew->zName must be "sqlite_altertab_<zTabName>" as code expects to skip first 16 chars */
  pNew->zName = sqlite3MPrintf(db, "sqlite_altertab_%s", zTabName);
  TEST_ASSERT_NOT_NULL(pNew->zName);
  /* Single column which is the new column */
  pNew->nCol = 1;
  pNew->aCol = (Column*)sqlite3DbMallocZero(db, sizeof(Column));
  TEST_ASSERT_NOT_NULL(pNew->aCol);
  /* Make sure this is treated as ordinary table */
  pNew->tabFlags = 0; /* IsOrdinaryTable() should pass */
  /* Some reasonable addColOffset value used by printf() in nested parse */
  pNew->u.tab.addColOffset = 1;
  return pNew;
}

/* Construct a TK_SPAN Expr whose pLeft has the given op (e.g., TK_NULL, TK_INTEGER, TK_FUNCTION) */
static Expr *makeSpanExprWithLeft(sqlite3 *db, int leftOp){
  Expr *pLeft = (Expr*)sqlite3DbMallocZero(db, sizeof(Expr));
  TEST_ASSERT_NOT_NULL(pLeft);
  pLeft->op = (u8)leftOp;
  Expr *pSpan = (Expr*)sqlite3DbMallocZero(db, sizeof(Expr));
  TEST_ASSERT_NOT_NULL(pSpan);
  pSpan->op = TK_SPAN;
  pSpan->pLeft = pLeft;
  return pSpan;
}

/* Initialize a Parse object with the given pNewTable and coldef Token. */
static void initParse(Parse *pParse, sqlite3 *db, Table *pNew, const char *zColDef, Token *pTokOut){
  memset(pParse, 0, sizeof(*pParse));
  pParse->db = db;
  db->pParse = pParse; /* Required by sqlite3AlterFinishAddColumn asserts */
  pParse->pNewTable = pNew;
  /* Token for column definition text */
  pTokOut->z = (const unsigned char*)zColDef;
  pTokOut->n = (int)strlen(zColDef);
  pTokOut->dyn = 0;
}

/* Cleanup minimal allocations done for pNewTable */
static void freeNewAlterTable(sqlite3 *db, Table *pNew){
  if( pNew ){
    if( pNew->aCol ){
      /* free any default expressions we might have attached */
      if( pNew->aCol[0].pDflt ){
        sqlite3ExprDelete(db, pNew->aCol[0].pDflt);
        pNew->aCol[0].pDflt = 0;
      }
      sqlite3DbFree(db, pNew->aCol);
    }
    if( pNew->zName ) sqlite3DbFree(db, pNew->zName);
    sqlite3DbFree(db, pNew);
  }
}

void setUp(void) {
  /* fresh in-memory db with base table */
  init_db_and_base_table("CREATE TABLE t1(a)");
}

void tearDown(void) {
  if( gDb ){
    sqlite3_close(gDb);
    gDb = NULL;
  }
}

/* Test: PRIMARY KEY on new column is rejected immediately with error message */
void test_sqlite3AlterFinishAddColumn_rejects_primary_key(void){
  Table *pNew = allocNewAlterTable(gDb, "t1");
  Column *pCol = &pNew->aCol[0];
  pCol->colFlags |= COLFLAG_PRIMKEY;

  Parse sParse;
  Token sTok;
  initParse(&sParse, gDb, pNew, "x INTEGER PRIMARY KEY", &sTok);

  sqlite3AlterFinishAddColumn(&sParse, &sTok);

  TEST_ASSERT_GREATER_THAN(0, sParse.nErr);
  TEST_ASSERT_NOT_NULL(sParse.zErrMsg);
  TEST_ASSERT_EQUAL_INT(0, strstr(sParse.zErrMsg, "Cannot add a PRIMARY KEY column")==NULL);

  freeNewAlterTable(gDb, pNew);
}

/* Test: UNIQUE constraint on new column is rejected immediately with error message */
void test_sqlite3AlterFinishAddColumn_rejects_unique(void){
  Table *pNew = allocNewAlterTable(gDb, "t1");
  Column *pCol = &pNew->aCol[0];
  pCol->colFlags &= ~COLFLAG_PRIMKEY; /* ensure not primary key */
  /* Any non-NULL pIndex indicates UNIQUE column in this code-path */
  pNew->pIndex = (Index*)pNew; /* dummy non-NULL */

  Parse sParse;
  Token sTok;
  initParse(&sParse, gDb, pNew, "x INTEGER UNIQUE", &sTok);

  sqlite3AlterFinishAddColumn(&sParse, &sTok);

  TEST_ASSERT_GREATER_THAN(0, sParse.nErr);
  TEST_ASSERT_NOT_NULL(sParse.zErrMsg);
  TEST_ASSERT_EQUAL_INT(0, strstr(sParse.zErrMsg, "Cannot add a UNIQUE column")==NULL);

  /* reset to avoid dangling pIndex into freed memory */
  pNew->pIndex = 0;
  freeNewAlterTable(gDb, pNew);
}

/* Test: NOT NULL with literal NULL default schedules runtime error (no immediate error, VDBE generated) */
void test_sqlite3AlterFinishAddColumn_notnull_with_null_default_generates_runtime_check(void){
  Table *pNew = allocNewAlterTable(gDb, "t1");
  Column *pCol = &pNew->aCol[0];
  pCol->notNull = 1; /* any non-zero triggers the check */
  /* Default is literal NULL: represented as TK_SPAN with pLeft->op == TK_NULL */
  pCol->pDflt = makeSpanExprWithLeft(gDb, TK_NULL);

  Parse sParse;
  Token sTok;
  initParse(&sParse, gDb, pNew, "x INTEGER NOT NULL DEFAULT NULL", &sTok);

  sqlite3AlterFinishAddColumn(&sParse, &sTok);

  TEST_ASSERT_EQUAL_INT(0, sParse.nErr);
  TEST_ASSERT_NOT_NULL(sParse.pVdbe); /* VDBE should be created due to nested parse and follow-up code */

  freeNewAlterTable(gDb, pNew);
}

/* Test: STORED generated column is rejected via runtime check path (no immediate error, VDBE generated) */
void test_sqlite3AlterFinishAddColumn_stored_generated_column_rejected_runtime(void){
  Table *pNew = allocNewAlterTable(gDb, "t1");
  Column *pCol = &pNew->aCol[0];
  pCol->colFlags |= (COLFLAG_GENERATED | COLFLAG_STORED);

  Parse sParse;
  Token sTok;
  initParse(&sParse, gDb, pNew, "x GENERATED ALWAYS AS (a+1) STORED", &sTok);

  sqlite3AlterFinishAddColumn(&sParse, &sTok);

  TEST_ASSERT_EQUAL_INT(0, sParse.nErr);
  TEST_ASSERT_NOT_NULL(sParse.pVdbe);

  freeNewAlterTable(gDb, pNew);
}

/* Test: Constant default value allowed (no immediate error, VDBE generated) */
void test_sqlite3AlterFinishAddColumn_constant_default_allowed(void){
  Table *pNew = allocNewAlterTable(gDb, "t1");
  Column *pCol = &pNew->aCol[0];
  /* Not generated column */
  pCol->colFlags &= ~COLFLAG_GENERATED;
  /* A simple constant default: represent as TK_SPAN with left TK_INTEGER */
  pCol->pDflt = makeSpanExprWithLeft(gDb, TK_INTEGER);

  Parse sParse;
  Token sTok;
  initParse(&sParse, gDb, pNew, "x INTEGER DEFAULT 5", &sTok);

  sqlite3AlterFinishAddColumn(&sParse, &sTok);

  TEST_ASSERT_EQUAL_INT(0, sParse.nErr);
  TEST_ASSERT_NOT_NULL(sParse.pVdbe);

  freeNewAlterTable(gDb, pNew);
}

/* Test: Non-constant default leads to runtime check (no immediate error, VDBE generated) */
void test_sqlite3AlterFinishAddColumn_nonconstant_default_generates_runtime_check(void){
  Table *pNew = allocNewAlterTable(gDb, "t1");
  Column *pCol = &pNew->aCol[0];
  /* Not generated */
  pCol->colFlags &= ~COLFLAG_GENERATED;
  /* Non-constant default: represent as TK_SPAN with left TK_FUNCTION (e.g., CURRENT_TIME) */
  pCol->pDflt = makeSpanExprWithLeft(gDb, TK_FUNCTION);

  Parse sParse;
  Token sTok;
  initParse(&sParse, gDb, pNew, "x TEXT DEFAULT (CURRENT_TIME)", &sTok);

  sqlite3AlterFinishAddColumn(&sParse, &sTok);

  TEST_ASSERT_EQUAL_INT(0, sParse.nErr);
  TEST_ASSERT_NOT_NULL(sParse.pVdbe);

  freeNewAlterTable(gDb, pNew);
}

int main(void){
  UNITY_BEGIN();
  RUN_TEST(test_sqlite3AlterFinishAddColumn_rejects_primary_key);
  RUN_TEST(test_sqlite3AlterFinishAddColumn_rejects_unique);
  RUN_TEST(test_sqlite3AlterFinishAddColumn_notnull_with_null_default_generates_runtime_check);
  RUN_TEST(test_sqlite3AlterFinishAddColumn_stored_generated_column_rejected_runtime);
  RUN_TEST(test_sqlite3AlterFinishAddColumn_constant_default_allowed);
  RUN_TEST(test_sqlite3AlterFinishAddColumn_nonconstant_default_generates_runtime_check);
  return UNITY_END();
}