package tests

import (
	"fmt"
	"sync"
	"testing"
	"time"

	"github.com/stretchr/testify/assert"
	"github.com/rockliang/poimen/workflows/internal/board"
	"github.com/rockliang/poimen/workflows/internal/pause"
	"github.com/rockliang/poimen/workflows/internal/recovery"
)

// TestConcurrentWorkflows tests multiple workflows executing concurrently
func TestConcurrentWorkflows(t *testing.T) {
	tmpDir := t.TempDir()
	numWorkflows := 5

	// Initialize shared managers
	snapshotMgr := pause.NewSnapshotManager(tmpDir)
	pauseHandler := pause.NewPauseHandler(snapshotMgr)
	stateTracker := board.NewStateTracker(tmpDir)

	var wg sync.WaitGroup
	errors := make(chan error, numWorkflows)

	// Launch concurrent workflows
	for i := 1; i <= numWorkflows; i++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()

			workflowID := fmt.Sprintf("wf-%d", id)

			// Save snapshot
			_, err := pauseHandler.SaveSnapshot(
				workflowID,
				"implement",
				[]string{fmt.Sprintf("T%d.1", id)},
				[]string{fmt.Sprintf("T%d.2", id)},
				nil,
				fmt.Sprintf("T%d.2", id),
				"activity-1",
				nil,
				nil,
				nil,
			)
			if err != nil {
				errors <- fmt.Errorf("wf-%d: snapshot failed: %v", id, err)
				return
			}

			// Update state
			err = stateTracker.UpdateTaskState(fmt.Sprintf("T%d.1", id), "completed", "branch", nil)
			if err != nil {
				errors <- fmt.Errorf("wf-%d: state update failed: %v", id, err)
				return
			}

			// Pause and resume
			err = pauseHandler.RequestPause(&pause.PauseSignal{
				WorkflowID:  workflowID,
				Reason:      "test pause",
				RequestedAt: time.Now(),
			})
			if err != nil {
				errors <- fmt.Errorf("wf-%d: pause failed: %v", id, err)
				return
			}

			err = pauseHandler.RequestResume(&pause.ResumeSignal{
				WorkflowID:  workflowID,
				Reason:      "test resume",
				RequestedAt: time.Now(),
			})
			if err != nil {
				errors <- fmt.Errorf("wf-%d: resume failed: %v", id, err)
				return
			}
		}(i)
	}

	wg.Wait()
	close(errors)

	// Check for errors
	for err := range errors {
		assert.NoError(t, err)
	}

	// Verify all workflows were tracked
	states := pauseHandler.GetAllPauseStates()
	assert.Equal(t, numWorkflows, len(states))
}

// TestConcurrentBoardOperations tests concurrent board validation and healing
func TestConcurrentBoardOperations(t *testing.T) {
	boardContent := `# Task Board — Milestone T1: Production Hardening

**Submilestone:** T1 (Error recovery, observability, metrics, reliability)

| ID | Scope | Status | Branch | Verification |
|----|-------|--------|--------|--------------|
| T1.1 | Task 1 | [x] | task/T1.1 | Verify recovery works |
| T1.2 | Task 2 | [x] | task/T1.2 | Verify metrics visible |
| T1.3 | Task 3 | [ ] | task/T1.3 | Verify recommendations |
| T1.4 | Task 4 | [ ] | task/T1.4 | Verify healing works |
`

	validator := board.NewBoardValidator("")
	numValidations := 10

	var wg sync.WaitGroup
	errors := make(chan error, numValidations)

	for i := 0; i < numValidations; i++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()

			// Validate
			if !validator.ValidateBoard(boardContent) {
				errors <- fmt.Errorf("validation %d failed", id)
				return
			}

			// Parse
			tasks, err := validator.ParseTasks(boardContent)
			if err != nil {
				errors <- fmt.Errorf("parse %d failed: %v", id, err)
				return
			}

			if len(tasks) != 4 {
				errors <- fmt.Errorf("validation %d: expected 4 tasks, got %d", id, len(tasks))
				return
			}
		}(i)
	}

	wg.Wait()
	close(errors)

	for err := range errors {
		assert.NoError(t, err)
	}
}

// TestConcurrentStateTracking tests concurrent state updates
func TestConcurrentStateTracking(t *testing.T) {
	tmpDir := t.TempDir()
	tracker := board.NewStateTracker(tmpDir)
	numTasks := 20
	var wg sync.WaitGroup

	// Concurrent state updates
	for i := 1; i <= numTasks; i++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()

			taskID := fmt.Sprintf("T%d", id)
			_ = tracker.UpdateTaskState(taskID, "in_progress", "branch", nil)

			time.Sleep(time.Duration(id%5) * time.Millisecond)

			_ = tracker.UpdateTaskState(taskID, "completed", "branch", nil)
		}(i)
	}

	wg.Wait()

	completed := tracker.GetCompletedTasks()
	assert.Equal(t, numTasks, len(completed))
}

// TestConcurrentSnapshotCreation tests concurrent snapshot creation and restoration
func TestConcurrentSnapshotCreation(t *testing.T) {
	tmpDir := t.TempDir()
	snapMgr := pause.NewSnapshotManager(tmpDir)
	numSnapshots := 10
	var wg sync.WaitGroup

	// Create snapshots concurrently
	for i := 1; i <= numSnapshots; i++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()

			workflowID := fmt.Sprintf("wf-%d", id)
			_, _ = snapMgr.CreateSnapshot(
				workflowID,
				"stage",
				[]string{},
				[]string{},
				nil,
				"",
				"",
				nil,
				nil,
				nil,
			)
		}(i)
	}

	wg.Wait()

	// Restore snapshots
	for i := 1; i <= numSnapshots; i++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()

			workflowID := fmt.Sprintf("wf-%d", id)
			snapshot, err := snapMgr.RestoreFromSnapshot(workflowID)
			assert.NoError(t, err)
			assert.NotNil(t, snapshot)
		}(i)
	}

	wg.Wait()
}

// TestRecoveryWithConcurrency tests retry policies under concurrent load
func TestRecoveryWithConcurrency(t *testing.T) {
	retryPolicy := recovery.ActivityRetryPolicy()
	assert.NotNil(t, retryPolicy)

	numAttempts := 20
	var wg sync.WaitGroup

	for i := 0; i < numAttempts; i++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()

			rc := recovery.RetryCount{Current: 0, Maximum: 3}
			for rc.CanRetry() {
				rc.Increment()
				time.Sleep(time.Millisecond)
			}
			assert.Equal(t, 3, rc.Current)
		}(i)
	}

	wg.Wait()
}

// TestIntegrationHealthCheck tests health checks under concurrent operations
func TestIntegrationHealthCheck(t *testing.T) {
	tmpDir := t.TempDir()
	
	// Simulate concurrent operations with health checks
	var wg sync.WaitGroup
	numConcurrent := 5

	for i := 0; i < numConcurrent; i++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()
			
			// Simulate workflow with state changes
			stateTracker := board.NewStateTracker(tmpDir)
			_ = stateTracker.UpdateTaskState("T1", "in_progress", "branch", nil)
			
			stats := stateTracker.GetStats()
			assert.Equal(t, 1, stats["total"])
			
			_ = stateTracker.UpdateTaskState("T1", "completed", "branch", nil)
		}(i)
	}

	wg.Wait()
}

// TestPauseResumeUnderLoad tests pause/resume with concurrent state changes
func TestPauseResumeUnderLoad(t *testing.T) {
	tmpDir := t.TempDir()
	pauseMgr := pause.NewSnapshotManager(tmpDir)
	pauseHandler := pause.NewPauseHandler(pauseMgr)

	numWorkflows := 10
	var wg sync.WaitGroup

	// Start workflows and pause them concurrently
	for i := 1; i <= numWorkflows; i++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()

			workflowID := fmt.Sprintf("wf-%d", id)

			// Save snapshot
			_, _ = pauseHandler.SaveSnapshot(
				workflowID,
				"stage",
				[]string{},
				[]string{},
				nil,
				"",
				"",
				nil,
				nil,
				nil,
			)

			// Pause
			_ = pauseHandler.RequestPause(&pause.PauseSignal{
				WorkflowID:  workflowID,
				Reason:      "load test",
				RequestedAt: time.Now(),
			})

			// Small delay to simulate work
			time.Sleep(time.Duration(id%3) * time.Millisecond)

			// Resume
			_ = pauseHandler.RequestResume(&pause.ResumeSignal{
				WorkflowID:  workflowID,
				Reason:      "load test resume",
				RequestedAt: time.Now(),
			})
		}(i)
	}

	wg.Wait()

	// Verify all workflows
	stats := pauseHandler.GetPauseStats()
	assert.Equal(t, numWorkflows, stats["total"])
}

// TestDataConsistencyUnderConcurrency ensures data consistency with concurrent access
func TestDataConsistencyUnderConcurrency(t *testing.T) {
	tmpDir := t.TempDir()
	tracker := board.NewStateTracker(tmpDir)

	const numGoroutines = 20
	const operationsPerGoroutine = 10

	var wg sync.WaitGroup

	// Concurrent reads and writes
	for g := 0; g < numGoroutines; g++ {
		wg.Add(1)
		go func() {
			defer wg.Done()

			for op := 0; op < operationsPerGoroutine; op++ {
				taskID := fmt.Sprintf("T%d", op%5)

				if op%2 == 0 {
					// Write
					_ = tracker.UpdateTaskState(taskID, "in_progress", "branch", nil)
				} else {
					// Read
					_ = tracker.GetTaskState(taskID)
				}
			}
		}()
	}

	wg.Wait()

	// Verify final state is consistent
	allStates := tracker.GetAllStates()
	assert.Greater(t, len(allStates), 0)
}

// TestNetworkFlakinessSim simulates network issues with retries
func TestNetworkFlakinessSim(t *testing.T) {
	retryPolicy := recovery.ActivityRetryPolicy()
	numAttempts := 0
	maxAttempts := retryPolicy.MaximumAttempts

	// Simulate retryable errors
	for numAttempts < int(maxAttempts) {
		numAttempts++
		time.Sleep(1 * time.Millisecond)
	}

	assert.Equal(t, 3, numAttempts)
}

// TestCrossWorkflowIsolation ensures workflows don't interfere with each other
func TestCrossWorkflowIsolation(t *testing.T) {
	tmpDir := t.TempDir()
	wf1Handler := pause.NewPauseHandler(pause.NewSnapshotManager(tmpDir))
	wf2Handler := pause.NewPauseHandler(pause.NewSnapshotManager(tmpDir))

	// Workflow 1
	_ = wf1Handler.RequestPause(&pause.PauseSignal{
		WorkflowID:  "wf-1",
		Reason:      "test",
		RequestedAt: time.Now(),
	})

	// Workflow 2 should not be affected
	assert.False(t, wf2Handler.IsPaused("wf-1"))
	assert.False(t, wf2Handler.IsPaused("wf-2"))

	_ = wf2Handler.RequestPause(&pause.PauseSignal{
		WorkflowID:  "wf-2",
		Reason:      "test",
		RequestedAt: time.Now(),
	})

	// Both should be paused independently
	assert.True(t, wf1Handler.IsPaused("wf-1"))
	assert.True(t, wf2Handler.IsPaused("wf-2"))
}

// BenchmarkConcurrentSnapshot benchmarks concurrent snapshot creation
func BenchmarkConcurrentSnapshot(b *testing.B) {
	tmpDir := b.TempDir()
	snapMgr := pause.NewSnapshotManager(tmpDir)

	b.RunParallel(func(pb *testing.PB) {
		i := 0
		for pb.Next() {
			workflowID := fmt.Sprintf("wf-bench-%d", i%100)
			_, _ = snapMgr.CreateSnapshot(
				workflowID,
				"stage",
				nil,
				nil,
				nil,
				"",
				"",
				nil,
				nil,
				nil,
			)
			i++
		}
	})
}

// BenchmarkConcurrentStateUpdate benchmarks concurrent state updates
func BenchmarkConcurrentStateUpdate(b *testing.B) {
	tmpDir := b.TempDir()
	tracker := board.NewStateTracker(tmpDir)

	b.RunParallel(func(pb *testing.PB) {
		i := 0
		for pb.Next() {
			taskID := fmt.Sprintf("T%d", i%50)
			_ = tracker.UpdateTaskState(taskID, "completed", "branch", nil)
			i++
		}
	})
}