package wazero_test

import (
	"context"
	_ "embed"
	"fmt"
	"log"
	"time"

	"github.com/tetratelabs/wazero"
)

// infiniteLoopWasm exports a function named "infinite_loop" that never exits.
//
//go:embed internal/integration_test/engine/testdata/infinite_loop.wasm
var infiniteLoopWasm []byte

// ExampleRuntimeConfig_WithCloseOnContextDone_context_timeout demonstrates how to ensure the termination
// of infinite loop function with context.Context created by context.WithTimeout powered by
// RuntimeConfig.WithEnsureTermination configuration.
func ExampleRuntimeConfig_WithCloseOnContextDone_context_timeout() {
	ctx := context.Background()

	r := wazero.NewRuntimeWithConfig(ctx,
		// Enables the WithCloseOnContextDone option.
		wazero.NewRuntimeConfig().WithCloseOnContextDone(true))
	defer r.Close(ctx)

	moduleInstance, err := r.InstantiateWithConfig(ctx, infiniteLoopWasm,
		wazero.NewModuleConfig().WithName("malicious_wasm"))
	if err != nil {
		log.Panicln(err)
	}

	infiniteLoop := moduleInstance.ExportedFunction("infinite_loop")

	// Create the context.Context to be passed to the invocation of infinite_loop.
	ctx, cancel := context.WithTimeout(ctx, time.Second)
	defer cancel()

	// Invoke the infinite loop with the timeout context.
	_, err = infiniteLoop.Call(ctx)

	// Timeout is correctly handled and triggers the termination of infinite loop.
	fmt.Println(err)

	// Output:
	//	module closed with context deadline exceeded
}

// ExampleRuntimeConfig_WithCloseOnContextDone_context_cancel demonstrates how to ensure the termination
// of infinite loop function with context.Context created by context.WithCancel powered by
// RuntimeConfig.WithEnsureTermination configuration.
func ExampleRuntimeConfig_WithCloseOnContextDone_context_cancel() {
	ctx := context.Background()

	r := wazero.NewRuntimeWithConfig(ctx,
		// Enables the WithCloseOnContextDone option.
		wazero.NewRuntimeConfig().WithCloseOnContextDone(true))
	defer r.Close(ctx)

	moduleInstance, err := r.InstantiateWithConfig(ctx, infiniteLoopWasm,
		wazero.NewModuleConfig().WithName("malicious_wasm"))
	if err != nil {
		log.Panicln(err)
	}

	infiniteLoop := moduleInstance.ExportedFunction("infinite_loop")

	// Create the context.Context to be passed to the invocation of infinite_loop.
	ctx, cancel := context.WithCancel(ctx)
	go func() {
		// After 2 seconds, cancel the invocation of infinite loop.
		time.Sleep(2 * time.Second)
		cancel()
	}()

	// Invoke the infinite loop with the timeout context.
	_, err = infiniteLoop.Call(ctx)

	// context Cancellation is correctly handled and triggers the termination of infinite loop.
	fmt.Println(err)

	// Output:
	//	module closed with context canceled
}

// ExampleRuntimeConfig_WithCloseOnContextDone_moduleClose demonstrates how to ensure the termination
// of infinite loop function with api.Module's CloseWithExitCode method powered by
// RuntimeConfig.WithEnsureTermination configuration.
func ExampleRuntimeConfig_WithCloseOnContextDone_moduleClose() {
	ctx := context.Background()

	r := wazero.NewRuntimeWithConfig(ctx,
		// Enables the WithCloseOnContextDone option.
		wazero.NewRuntimeConfig().WithCloseOnContextDone(true))
	defer r.Close(ctx)

	moduleInstance, err := r.InstantiateWithConfig(ctx, infiniteLoopWasm,
		wazero.NewModuleConfig().WithName("malicious_wasm"))
	if err != nil {
		log.Panicln(err)
	}

	infiniteLoop := moduleInstance.ExportedFunction("infinite_loop")

	go func() {
		// After 2 seconds, close the module instance with CloseWithExitCode, which triggers the termination
		// of infinite loop.
		time.Sleep(2 * time.Second)
		if err := moduleInstance.CloseWithExitCode(ctx, 1); err != nil {
			log.Panicln(err)
		}
	}()

	// Invoke the infinite loop with the timeout context.
	_, err = infiniteLoop.Call(ctx)

	// The exit code is correctly handled and triggers the termination of infinite loop.
	fmt.Println(err)

	// Output:
	//	module closed with exit_code(1)
}