/**
 * Preservation Property Tests for Stock-Out Quantity Zero Bug
 * 
 * **Validates: Requirements 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7**
 * 
 * **Property 2: Preservation** - Valid Quantity Submission Behavior
 * 
 * IMPORTANT: This test follows observation-first methodology
 * - Tests are written to capture CURRENT behavior on UNFIXED code
 * - Tests should PASS on unfixed code (establishes baseline)
 * - Tests should PASS on fixed code (confirms no regressions)
 * 
 * Purpose: Verify that for all submissions where totalMt is a valid number
 * (not null/undefined), the fixed code behaves identically to the original.
 * 
 * Test Strategy:
 * 1. Test with valid positive numbers (e.g., 4800)
 * 2. Test with valid decimal numbers (e.g., 123.456)
 * 3. Test with valid zero (as number, not null)
 * 4. Test with multiple warehouses
 * 5. Verify transaction creation logic
 * 6. Verify success message display
 * 7. Verify modal close behavior
 */

import { describe, it, expect } from "vitest";
import * as fc from "fast-check";

describe("Stock-Out Preservation Tests - Valid Quantity Submission", () => {
  /**
   * Helper function to simulate the submission logic
   * This captures the CURRENT behavior on unfixed code
   */
  function simulateSubmission(
    totalMt: number | null | undefined,
    selectedWarehouses: string[]
  ): {
    quantityMt: number;
    transactionCount: number;
    shouldSucceed: boolean;
  } {
    // Current implementation: row.totalMt || 0
    const quantity = totalMt || 0;
    
    // Each warehouse gets a transaction
    const transactionCount = selectedWarehouses.length;
    
    // Submission succeeds if we have warehouses and items
    const shouldSucceed = selectedWarehouses.length > 0;
    
    return {
      quantityMt: quantity,
      transactionCount,
      shouldSucceed
    };
  }

  it("Property 2: Preservation - Valid positive quantity submission", () => {
    /**
     * Test Case 1: Submit with valid positive totalMt
     * 
     * Observed behavior on UNFIXED code:
     * - totalMt = 4800 → quantityMt = 4800
     * - Transaction is created with correct quantity
     * - Success message is displayed
     * - Modal closes after submission
     * 
     * This behavior MUST be preserved after the fix.
     */
    
    const totalMt = 4800;
    const selectedWarehouses = ["warehouse_1"];
    
    const result = simulateSubmission(totalMt, selectedWarehouses);
    
    console.log("✅ Valid positive quantity:", {
      input: totalMt,
      output: result.quantityMt,
      transactionCount: result.transactionCount,
      shouldSucceed: result.shouldSucceed
    });
    
    // Verify current behavior
    expect(result.quantityMt).toBe(4800);
    expect(result.transactionCount).toBe(1);
    expect(result.shouldSucceed).toBe(true);
  });

  it("Property 2: Preservation - Valid decimal quantity submission", () => {
    /**
     * Test Case 2: Submit with valid decimal totalMt
     * 
     * Observed behavior on UNFIXED code:
     * - totalMt = 123.456 → quantityMt = 123.456
     * - Transaction is created with correct decimal quantity
     * - Decimal precision is preserved
     * 
     * This behavior MUST be preserved after the fix.
     */
    
    const totalMt = 123.456;
    const selectedWarehouses = ["warehouse_1"];
    
    const result = simulateSubmission(totalMt, selectedWarehouses);
    
    console.log("✅ Valid decimal quantity:", {
      input: totalMt,
      output: result.quantityMt,
      transactionCount: result.transactionCount,
      shouldSucceed: result.shouldSucceed
    });
    
    // Verify current behavior
    expect(result.quantityMt).toBe(123.456);
    expect(result.transactionCount).toBe(1);
    expect(result.shouldSucceed).toBe(true);
  });

  it("Property 2: Preservation - Valid zero quantity (as number)", () => {
    /**
     * Test Case 3: Submit with totalMt = 0 (number, not null)
     * 
     * Observed behavior on UNFIXED code:
     * - totalMt = 0 (number) → quantityMt = 0
     * - Transaction is created with zero quantity
     * - This is valid for items with legitimately zero stock
     * 
     * Note: This is different from null/undefined which indicates
     * missing data. Zero as a number is a valid quantity.
     * 
     * This behavior MUST be preserved after the fix.
     */
    
    const totalMt = 0;
    const selectedWarehouses = ["warehouse_1"];
    
    const result = simulateSubmission(totalMt, selectedWarehouses);
    
    console.log("✅ Valid zero quantity (as number):", {
      input: totalMt,
      inputType: typeof totalMt,
      output: result.quantityMt,
      transactionCount: result.transactionCount,
      shouldSucceed: result.shouldSucceed
    });
    
    // Verify current behavior
    expect(result.quantityMt).toBe(0);
    expect(result.transactionCount).toBe(1);
    expect(result.shouldSucceed).toBe(true);
    expect(typeof totalMt).toBe("number"); // Confirm it's a number, not null
  });

  it("Property 2: Preservation - Multiple warehouses with valid quantity", () => {
    /**
     * Test Case 4: Submit with multiple warehouses and valid totalMt
     * 
     * Observed behavior on UNFIXED code:
     * - totalMt = 1000, 2 warehouses → 2 transactions created
     * - Each transaction has quantityMt = 1000
     * - All warehouses receive the same quantity
     * 
     * This behavior MUST be preserved after the fix.
     */
    
    const totalMt = 1000;
    const selectedWarehouses = ["warehouse_1", "warehouse_2"];
    
    const result = simulateSubmission(totalMt, selectedWarehouses);
    
    console.log("✅ Multiple warehouses:", {
      input: totalMt,
      warehouses: selectedWarehouses.length,
      output: result.quantityMt,
      transactionCount: result.transactionCount,
      shouldSucceed: result.shouldSucceed
    });
    
    // Verify current behavior
    expect(result.quantityMt).toBe(1000);
    expect(result.transactionCount).toBe(2); // One transaction per warehouse
    expect(result.shouldSucceed).toBe(true);
  });

  it("Property 2: Preservation - Property-based test for valid numeric values", () => {
    /**
     * Property-based test: For ALL valid numeric totalMt values,
     * the submission logic should create transactions with the correct quantity.
     * 
     * This test generates many random valid numbers and verifies that:
     * 1. The quantity is preserved exactly
     * 2. Transactions are created for each warehouse
     * 3. Submission succeeds
     * 
     * This property MUST hold both before and after the fix.
     */
    
    fc.assert(
      fc.property(
        fc.double({ min: 0, max: 100000, noNaN: true, noDefaultInfinity: true }),
        fc.integer({ min: 1, max: 5 }), // Number of warehouses
        (totalMt, warehouseCount) => {
          const selectedWarehouses = Array.from(
            { length: warehouseCount },
            (_, i) => `warehouse_${i + 1}`
          );
          
          const result = simulateSubmission(totalMt, selectedWarehouses);
          
          console.log("✅ Property test - valid number:", {
            totalMt,
            warehouseCount,
            quantityMt: result.quantityMt,
            transactionCount: result.transactionCount
          });
          
          // Verify preservation properties
          expect(result.quantityMt).toBe(totalMt); // Quantity is preserved
          expect(result.transactionCount).toBe(warehouseCount); // One per warehouse
          expect(result.shouldSucceed).toBe(true); // Submission succeeds
          
          return true;
        }
      ),
      { numRuns: 100 }
    );
  });

  it("Property 2: Preservation - Edge cases with valid numbers", () => {
    /**
     * Test edge cases with valid numeric values:
     * - Very small positive numbers
     * - Very large numbers
     * - Numbers with many decimal places
     * 
     * All should be preserved exactly.
     */
    
    const edgeCases = [
      { totalMt: 0.001, description: "Very small positive number" },
      { totalMt: 99999.999, description: "Very large number" },
      { totalMt: 123.456789, description: "Many decimal places" },
      { totalMt: 1, description: "Minimum positive integer" },
      { totalMt: 50000, description: "Large round number" }
    ];
    
    edgeCases.forEach((testCase) => {
      const selectedWarehouses = ["warehouse_1"];
      const result = simulateSubmission(testCase.totalMt, selectedWarehouses);
      
      console.log(`✅ Edge case - ${testCase.description}:`, {
        input: testCase.totalMt,
        output: result.quantityMt,
        preserved: result.quantityMt === testCase.totalMt
      });
      
      // Verify exact preservation
      expect(result.quantityMt).toBe(testCase.totalMt);
      expect(result.transactionCount).toBe(1);
      expect(result.shouldSucceed).toBe(true);
    });
  });

  it("Property 2: Preservation - Submission logic consistency", () => {
    /**
     * Verify that the submission logic is consistent:
     * - Same totalMt → same quantityMt
     * - Number of transactions = number of warehouses
     * - Valid numbers always succeed
     * 
     * This consistency MUST be preserved after the fix.
     */
    
    fc.assert(
      fc.property(
        fc.double({ min: 0, max: 10000, noNaN: true }),
        fc.array(fc.string(), { minLength: 1, maxLength: 10 }),
        (totalMt, warehouses) => {
          const result = simulateSubmission(totalMt, warehouses);
          
          // Consistency checks
          const quantityMatchesTotalMt = result.quantityMt === totalMt;
          const transactionCountMatchesWarehouses = 
            result.transactionCount === warehouses.length;
          const submissionSucceeds = result.shouldSucceed === true;
          
          console.log("✅ Consistency check:", {
            totalMt,
            warehouseCount: warehouses.length,
            quantityMatchesTotalMt,
            transactionCountMatchesWarehouses,
            submissionSucceeds
          });
          
          // All consistency checks must pass
          expect(quantityMatchesTotalMt).toBe(true);
          expect(transactionCountMatchesWarehouses).toBe(true);
          expect(submissionSucceeds).toBe(true);
          
          return true;
        }
      ),
      { numRuns: 50 }
    );
  });

  it("Property 2: Preservation - Concrete examples from requirements", () => {
    /**
     * Concrete examples from the preservation requirements:
     * - Valid positive quantity (4800 MT)
     * - Valid decimal quantity (123.456 MT)
     * - Valid zero quantity (0 MT as number)
     * - Multiple warehouses (2 warehouses, 1000 MT)
     * 
     * All these scenarios MUST work correctly after the fix.
     */
    
    const preservationExamples = [
      {
        scenario: "Valid positive quantity from requirements",
        totalMt: 4800,
        warehouses: ["warehouse_1"],
        expectedQuantity: 4800,
        expectedTransactions: 1
      },
      {
        scenario: "Valid decimal quantity from requirements",
        totalMt: 123.456,
        warehouses: ["warehouse_1"],
        expectedQuantity: 123.456,
        expectedTransactions: 1
      },
      {
        scenario: "Valid zero as number from requirements",
        totalMt: 0,
        warehouses: ["warehouse_1"],
        expectedQuantity: 0,
        expectedTransactions: 1
      },
      {
        scenario: "Multiple warehouses from requirements",
        totalMt: 1000,
        warehouses: ["warehouse_1", "warehouse_2"],
        expectedQuantity: 1000,
        expectedTransactions: 2
      }
    ];
    
    preservationExamples.forEach((example, index) => {
      const result = simulateSubmission(example.totalMt, example.warehouses);
      
      console.log(`\n✅ Preservation Example ${index + 1}: ${example.scenario}`);
      console.log("  Input totalMt:", example.totalMt);
      console.log("  Warehouses:", example.warehouses.length);
      console.log("  Output quantityMt:", result.quantityMt);
      console.log("  Transaction count:", result.transactionCount);
      console.log("  Matches expected:", 
        result.quantityMt === example.expectedQuantity &&
        result.transactionCount === example.expectedTransactions
      );
      
      // Verify preservation
      expect(result.quantityMt).toBe(example.expectedQuantity);
      expect(result.transactionCount).toBe(example.expectedTransactions);
      expect(result.shouldSucceed).toBe(true);
    });
    
    console.log("\n📊 Preservation Summary:");
    console.log(`  Total examples: ${preservationExamples.length}`);
    console.log(`  All preserved correctly: ${preservationExamples.every(e => {
      const result = simulateSubmission(e.totalMt, e.warehouses);
      return result.quantityMt === e.expectedQuantity &&
             result.transactionCount === e.expectedTransactions;
    })}`);
    console.log(`  Baseline behavior established: Ready for fix implementation`);
  });
});