/*
 * Copyright 2024 CloudWeGo Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package compose

import (
	"context"
	"errors"
	"testing"
	"time"

	"github.com/stretchr/testify/assert"

	"github.com/cloudwego/eino/schema"
)

func TestCommonError(t *testing.T) {
	g := NewGraph[string, string]()
	assert.NoError(t, g.AddLambdaNode("1", InvokableLambda(func(ctx context.Context, input string) (output string, err error) {
		return "", errors.New("my error")
	})))
	assert.NoError(t, g.AddEdge(START, "1"))
	assert.NoError(t, g.AddEdge("1", END))

	ctx := context.Background()
	r, err := g.Compile(ctx)
	assert.NoError(t, err)

	// node error
	_, err = r.Invoke(ctx, "input")
	var ie *internalError

	assert.True(t, errors.As(err, &ie))
	assert.Equal(t, "my error", ie.origError.Error())

	// wrapper error
	sr, sw := schema.Pipe[string](0)
	sw.Close()
	_, err = r.Transform(ctx, sr)
	assert.True(t, errors.As(err, &ie))
	assert.ErrorContains(t, ie.origError, "stream reader is empty, concat fail")
	assert.Equal(t, []string{"1"}, ie.nodePath.path)
	println(err.Error())
}

func TestSubGraphNodeError(t *testing.T) {
	subG := NewGraph[string, string]()
	assert.NoError(t, subG.AddLambdaNode("1", InvokableLambda(func(ctx context.Context, input string) (output string, err error) {
		return "", errors.New("my error")
	})))
	assert.NoError(t, subG.AddEdge(START, "1"))
	assert.NoError(t, subG.AddEdge("1", END))

	g := NewGraph[string, string]()
	assert.NoError(t, g.AddGraphNode("a", subG))
	assert.NoError(t, g.AddEdge(START, "a"))
	assert.NoError(t, g.AddEdge("a", END))

	ctx := context.Background()
	r, err := g.Compile(ctx)
	assert.NoError(t, err)
	_, err = r.Invoke(ctx, "input")
	var ie *internalError
	assert.True(t, errors.As(err, &ie))
	assert.Equal(t, "my error", ie.origError.Error())
	assert.Equal(t, []string{"a", "1"}, ie.nodePath.path)
}

func TestContextCancelDuringRun(t *testing.T) {
	// Create a graph with a long-running node to test context cancellation
	g := NewGraph[string, string]()

	// Add a node that waits for some time (long enough to be cancelled)
	assert.NoError(t, g.AddLambdaNode("slow_node", InvokableLambda(func(ctx context.Context, input string) (output string, err error) {
		select {
		case <-ctx.Done():
			// Return context's error when cancelled
			return "", ctx.Err()
		case <-time.After(200 * time.Millisecond):
			return input + "_processed", nil
		}
	})))

	assert.NoError(t, g.AddEdge(START, "slow_node"))
	assert.NoError(t, g.AddEdge("slow_node", END))

	// Create a context that we can cancel
	ctx, cancel := context.WithCancel(context.Background())

	// Compile the graph
	r, err := g.Compile(ctx)
	assert.NoError(t, err)

	// Run the invoke in a goroutine
	resultCh := make(chan error)
	go func() {
		_, err := r.Invoke(ctx, "input")
		resultCh <- err
	}()

	// Cancel the context after a short delay
	time.Sleep(50 * time.Millisecond)
	cancel()

	// Get the result
	err = <-resultCh

	// Verify the error is related to context cancellation
	assert.Error(t, err)

	// Check error type and content
	var ie *internalError
	assert.True(t, errors.As(err, &ie))

	// Error path should contain the node
	assert.Equal(t, []string{"slow_node"}, ie.nodePath.path)

	// Original error should be context.Canceled
	assert.ErrorIs(t, ie.origError, context.Canceled)

	// Test unwrap capability
	unwrappedErr := ie.Unwrap()
	assert.ErrorIs(t, unwrappedErr, context.Canceled)
}