# Implementation Plan: Yearly Statistics Display Logic

## Overview

This implementation plan modifies the `GetYearlyStatisticsByMonthAsync` method to support a rolling 15-month display window that adapts based on the current month. The implementation adds two new helper methods and refactors the main method logic.

## Tasks

- [x] 1. Create helper method for calculating display window
  - Implement `CalculateDisplayWindow` method that takes current year and month as parameters
  - Calculate start month/year by subtracting 3 months from current (handle year boundary)
  - Calculate end month/year by adding 11 months to current (handle year boundary)
  - Return tuple of (startYear, startMonth, endYear, endMonth)
  - Add unit tests for various current months (January, March, September, October, December)
  - _Requirements: 1.1, 1.2, 1.3, 1.4, 5.1, 6.1, 7.1, 8.1, 9.1, 10.1_

- [ ]* 1.1 Write unit tests for CalculateDisplayWindow
  - Test January: should return (previousYear, 10, currentYear, 11)
  - Test March: should return (previousYear, 12, currentYear, 2)
  - Test September: should return (currentYear, 6, currentYear + 1, 8)
  - Test October: should return (currentYear, 7, currentYear + 1, 9)
  - Test December: should return (currentYear, 9, currentYear + 1, 11)
  - _Requirements: 1.2, 1.3, 1.4, 5.1, 6.1, 7.1, 8.1, 9.1_

- [x] 2. Create helper method for zero statistics
  - Implement `CreateZeroStatistics` method that takes year and month as parameters
  - Create SecondaryCircuitInspectionStatisticsOutput with all counts set to 0
  - Set StatisticsStartTime to first day of month
  - Set StatisticsEndTime to last millisecond of month
  - Initialize empty StatisticsByModule list
  - _Requirements: 4.1, 4.3, 4.4_

- [ ]* 2.1 Write unit test for CreateZeroStatistics
  - Verify all count fields are 0
  - Verify StatisticsStartTime is correct
  - Verify StatisticsEndTime is correct
  - Verify StatisticsByModule is empty
  - _Requirements: 4.1, 4.3, 4.4_

- [x] 3. Refactor GetYearlyStatisticsByMonthAsync main logic
  - [x] 3.1 Update method to use current date instead of year parameter
    - Get current DateTime.Now
    - Extract currentYear and currentMonth
    - Log that year parameter is ignored for rolling window
    - _Requirements: 10.1, 12.5_

  - [x] 3.2 Calculate display window using helper method
    - Call CalculateDisplayWindow(currentYear, currentMonth)
    - Store returned startYear, startMonth, endYear, endMonth
    - _Requirements: 1.1, 5.1, 6.1, 7.1, 8.1, 9.1, 10.1_

  - [x] 3.3 Implement month iteration logic
    - Create loop to iterate from (startYear, startMonth) to (endYear, endMonth)
    - Handle year boundary crossing in loop
    - For each month, determine if it's historical, predicted, or zero
    - _Requirements: 10.2, 11.3, 12.4_

  - [x] 3.4 Implement historical data retrieval
    - For months <= currentMonth (accounting for year), call GetStatisticsAsync
    - Use dateRange format "yyyy-MM"
    - Add to historicalMonthlyStats list for prediction
    - Mark as IsPredicted = false
    - _Requirements: 1.5, 2.1, 2.2, 2.3_

  - [x] 3.5 Implement predicted data generation
    - For months currentMonth + 1 to currentMonth + 3, use prediction algorithm
    - Call PredictMonthlyStatisticsWithModuleDetails once with 3 months
    - Handle year boundary for prediction start month
    - Mark as IsPredicted = true
    - _Requirements: 3.1, 3.2, 3.3, 3.4_

  - [x] 3.6 Implement zero data generation
    - For months beyond currentMonth + 3, call CreateZeroStatistics
    - Mark as IsPredicted = false
    - _Requirements: 4.1, 4.3, 4.4_

  - [x] 3.7 Handle September special case
    - When currentMonth == 9, adjust display window to Jan-Dec of current year only
    - Ensure only 12 months are returned
    - _Requirements: 5.1, 5.2, 5.3, 5.4, 5.5_

  - [x] 3.8 Add error handling for individual month failures
    - Wrap each month's data retrieval in try-catch
    - On failure, use CreateZeroStatistics instead of failing entire request
    - Log warning for failed months
    - _Requirements: 11.4_

- [ ] 4. Checkpoint - Ensure all tests pass
  - Run all unit tests
  - Verify no compilation errors
  - Ask the user if questions arise

- [ ]* 5. Write property-based tests
  - [ ]* 5.1 Write property test for three historical months
    - **Property 1: Three Historical Months Preceding Current**
    - **Validates: Requirements 1.1, 1.5**
    - Generate random current months (April-December)
    - Verify 3 preceding months are in window with actual data
    - Verify IsPredicted = false for historical months

  - [ ]* 5.2 Write property test for current month inclusion
    - **Property 2: Current Month Inclusion and Marking**
    - **Validates: Requirements 2.1, 2.2, 2.3**
    - Generate random current months
    - Verify current month is in window
    - Verify IsPredicted = false
    - Verify data is not zero

  - [ ]* 5.3 Write property test for predicted months
    - **Property 3: Three Predicted Months Following Current**
    - **Validates: Requirements 3.1, 3.2, 3.3, 3.4**
    - Generate random current months
    - Verify next 3 months are in window
    - Verify IsPredicted = true
    - Verify year boundary handling

  - [ ]* 5.4 Write property test for zero data range
    - **Property 4: Zero Data Beyond Prediction Range**
    - **Validates: Requirements 4.1, 4.3, 4.4**
    - Generate random current months
    - Verify months beyond current + 3 have all zeros
    - Verify IsPredicted = false
    - Verify empty StatisticsByModule

  - [ ]* 5.5 Write property test for display window size
    - **Property 5: Display Window Size**
    - **Validates: Requirements 10.2, 12.2**
    - Generate random current months
    - Verify 15 months for all except September
    - Verify 12 months for September

  - [ ]* 5.6 Write property test for chronological sequence
    - **Property 6: Chronological Month Sequence**
    - **Validates: Requirements 11.3, 12.4**
    - Generate random current months
    - Verify each month is exactly 1 month after previous
    - Verify year increments correctly at boundaries

  - [ ]* 5.7 Write property test for month and year validity
    - **Property 7: Month and Year Value Validity**
    - **Validates: Requirements 11.1, 11.2**
    - Generate random current months
    - Verify all month values are 1-12
    - Verify all year values are valid (>= 1900, <= 9999)

  - [ ]* 5.8 Write property test for output year property
    - **Property 8: Output Year Property**
    - **Validates: Requirements 12.5**
    - Generate random current months
    - Verify output.Year equals current year

- [ ]* 6. Write integration tests
  - Test with real GetStatisticsAsync calls (using test database or mocks)
  - Test with real prediction algorithm
  - Test end-to-end flow for various current months
  - _Requirements: All_

- [x] 7. Update logging
  - Add log statement when year parameter is ignored
  - Add log statements for display window calculation
  - Add log statements for each month type (historical/predicted/zero)
  - _Requirements: All_

- [ ] 8. Final checkpoint - Ensure all tests pass
  - Run all unit tests
  - Run all property-based tests (minimum 100 iterations each)
  - Run integration tests
  - Verify no compilation errors
  - Ask the user if questions arise

## Notes

- Tasks marked with `*` are optional and can be skipped for faster MVP
- Each task references specific requirements for traceability
- Property tests should run minimum 100 iterations
- The year parameter is validated but not used in the new logic (for backward compatibility)
- September is a special case that returns only 12 months instead of 15