package templates

import (
	"fmt"
	"io"
	"path/filepath"
	"reflect"
	"strings"

	"github.com/pkg/errors"
	"gopkg.in/yaml.v2"

	"github.com/projectdiscovery/nuclei/v2/pkg/js/compiler"
	"github.com/projectdiscovery/nuclei/v2/pkg/operators"
	"github.com/projectdiscovery/nuclei/v2/pkg/protocols"
	"github.com/projectdiscovery/nuclei/v2/pkg/protocols/offlinehttp"
	"github.com/projectdiscovery/nuclei/v2/pkg/templates/cache"
	"github.com/projectdiscovery/nuclei/v2/pkg/templates/signer"
	"github.com/projectdiscovery/nuclei/v2/pkg/tmplexec"
	"github.com/projectdiscovery/nuclei/v2/pkg/utils"
	"github.com/projectdiscovery/retryablehttp-go"
	errorutil "github.com/projectdiscovery/utils/errors"
	fileutil "github.com/projectdiscovery/utils/file"
	stringsutil "github.com/projectdiscovery/utils/strings"
)

var (
	ErrCreateTemplateExecutor          = errors.New("cannot create template executer")
	ErrIncompatibleWithOfflineMatching = errors.New("template can't be used for offline matching")
)

var parsedTemplatesCache *cache.Templates

func init() {
	parsedTemplatesCache = cache.New()
}

// Parse parses a yaml request template file
// TODO make sure reading from the disk the template parsing happens once: see parsers.ParseTemplate vs templates.Parse
//
//nolint:gocritic // this cannot be passed by pointer
func Parse(filePath string, preprocessor Preprocessor, options protocols.ExecutorOptions) (*Template, error) {
	if !options.DoNotCache {
		if value, err := parsedTemplatesCache.Has(filePath); value != nil {
			return value.(*Template), err
		}
	}

	var reader io.ReadCloser
	if utils.IsURL(filePath) {
		// use retryablehttp (tls verification is enabled by default in the standard library)
		resp, err := retryablehttp.DefaultClient().Get(filePath)
		if err != nil {
			return nil, err
		}
		reader = resp.Body
	} else {
		var err error
		reader, err = options.Catalog.OpenFile(filePath)
		if err != nil {
			return nil, err
		}
	}
	defer reader.Close()
	options.TemplatePath = filePath
	template, err := ParseTemplateFromReader(reader, preprocessor, options.Copy())
	if err != nil {
		return nil, err
	}
	// Compile the workflow request
	if len(template.Workflows) > 0 {
		compiled := &template.Workflow

		compileWorkflow(filePath, preprocessor, &options, compiled, options.WorkflowLoader)
		template.CompiledWorkflow = compiled
		template.CompiledWorkflow.Options = &options
	}
	template.Path = filePath
	if !options.DoNotCache {
		parsedTemplatesCache.Store(filePath, template, err)
	}
	return template, nil
}

// parseSelfContainedRequests parses the self contained template requests.
func (template *Template) parseSelfContainedRequests() {
	if template.Signature.Value.String() != "" {
		for _, request := range template.RequestsHTTP {
			request.Signature = template.Signature
		}
	}
	if !template.SelfContained {
		return
	}
	for _, request := range template.RequestsHTTP {
		request.SelfContained = true
	}
	for _, request := range template.RequestsNetwork {
		request.SelfContained = true
	}
}

// Requests returns the total request count for the template
func (template *Template) Requests() int {
	return len(template.RequestsDNS) +
		len(template.RequestsHTTP) +
		len(template.RequestsFile) +
		len(template.RequestsNetwork) +
		len(template.RequestsHeadless) +
		len(template.Workflows) +
		len(template.RequestsSSL) +
		len(template.RequestsWebsocket) +
		len(template.RequestsWHOIS) +
		len(template.RequestsCode) +
		len(template.RequestsJavascript)
}

// compileProtocolRequests compiles all the protocol requests for the template
func (template *Template) compileProtocolRequests(options protocols.ExecutorOptions) error {
	templateRequests := template.Requests()

	if templateRequests == 0 {
		return fmt.Errorf("no requests defined for %s", template.ID)
	}

	if options.Options.OfflineHTTP {
		return template.compileOfflineHTTPRequest(options)
	}

	var requests []protocols.Request

	if template.hasMultipleRequests() {
		// when multiple requests are present preserve the order of requests and protocols
		// which is already done during unmarshalling
		requests = template.RequestsQueue
		if options.Flow == "" {
			options.IsMultiProtocol = true
		}
	} else {
		if len(template.RequestsDNS) > 0 {
			requests = append(requests, template.convertRequestToProtocolsRequest(template.RequestsDNS)...)
		}
		if len(template.RequestsFile) > 0 {
			requests = append(requests, template.convertRequestToProtocolsRequest(template.RequestsFile)...)
		}
		if len(template.RequestsNetwork) > 0 {
			requests = append(requests, template.convertRequestToProtocolsRequest(template.RequestsNetwork)...)
		}
		if len(template.RequestsHTTP) > 0 {
			requests = append(requests, template.convertRequestToProtocolsRequest(template.RequestsHTTP)...)
		}
		if len(template.RequestsHeadless) > 0 && options.Options.Headless {
			requests = append(requests, template.convertRequestToProtocolsRequest(template.RequestsHeadless)...)
		}
		if len(template.RequestsSSL) > 0 {
			requests = append(requests, template.convertRequestToProtocolsRequest(template.RequestsSSL)...)
		}
		if len(template.RequestsWebsocket) > 0 {
			requests = append(requests, template.convertRequestToProtocolsRequest(template.RequestsWebsocket)...)
		}
		if len(template.RequestsWHOIS) > 0 {
			requests = append(requests, template.convertRequestToProtocolsRequest(template.RequestsWHOIS)...)
		}
		if len(template.RequestsCode) > 0 {
			requests = append(requests, template.convertRequestToProtocolsRequest(template.RequestsCode)...)
		}
		if len(template.RequestsJavascript) > 0 {
			requests = append(requests, template.convertRequestToProtocolsRequest(template.RequestsJavascript)...)
		}
	}
	template.Executer = tmplexec.NewTemplateExecuter(requests, &options)
	return nil
}

// convertRequestToProtocolsRequest is a convenience wrapper to convert
// arbitrary interfaces which are slices of requests from the template to a
// slice of protocols.Request interface items.
func (template *Template) convertRequestToProtocolsRequest(requests interface{}) []protocols.Request {
	switch reflect.TypeOf(requests).Kind() {
	case reflect.Slice:
		s := reflect.ValueOf(requests)

		requestSlice := make([]protocols.Request, s.Len())
		for i := 0; i < s.Len(); i++ {
			value := s.Index(i)
			valueInterface := value.Interface()
			requestSlice[i] = valueInterface.(protocols.Request)
		}
		return requestSlice
	}
	return nil
}

// compileOfflineHTTPRequest iterates all requests if offline http mode is
// specified and collects all matchers for all the base request templates
// (those with URL {{BaseURL}} and it's slash variation.)
func (template *Template) compileOfflineHTTPRequest(options protocols.ExecutorOptions) error {
	operatorsList := []*operators.Operators{}

mainLoop:
	for _, req := range template.RequestsHTTP {
		hasPaths := len(req.Path) > 0
		if !hasPaths {
			break mainLoop
		}
		for _, path := range req.Path {
			pathIsBaseURL := stringsutil.EqualFoldAny(path, "{{BaseURL}}", "{{BaseURL}}/", "/")
			if !pathIsBaseURL {
				break mainLoop
			}
		}
		operatorsList = append(operatorsList, &req.Operators)
	}
	if len(operatorsList) > 0 {
		options.Operators = operatorsList
		template.Executer = tmplexec.NewTemplateExecuter([]protocols.Request{&offlinehttp.Request{}}, &options)
		return nil
	}

	return ErrIncompatibleWithOfflineMatching
}

// ParseTemplateFromReader reads the template from reader
// returns the parsed template
func ParseTemplateFromReader(reader io.Reader, preprocessor Preprocessor, options protocols.ExecutorOptions) (*Template, error) {
	template := &Template{}
	data, err := io.ReadAll(reader)
	if err != nil {
		return nil, err
	}

	data = template.expandPreprocessors(data)
	if preprocessor != nil {
		data = preprocessor.Process(data)
	}

	if err := yaml.Unmarshal(data, template); err != nil {
		return nil, err
	}

	if utils.IsBlank(template.Info.Name) {
		return nil, errors.New("no template name field provided")
	}
	if template.Info.Authors.IsEmpty() {
		return nil, errors.New("no template author field provided")
	}

	// Setting up variables regarding template metadata
	options.TemplateID = template.ID
	options.TemplateInfo = template.Info
	options.StopAtFirstMatch = template.StopAtFirstMatch

	if template.Variables.Len() > 0 {
		options.Variables = template.Variables
	}

	// if more than 1 request per protocol exist we add request id to protocol request
	// since in template context we have proto_prefix for each protocol it is overwritten
	// if request id is not present
	template.validateAllRequestIDs()

	// TODO: we should add a syntax check here or somehow use a javascript linter
	// simplest option for now seems to compile using goja and see if it fails
	if strings.TrimSpace(template.Flow) != "" {
		if len(template.Flow) > 0 && filepath.Ext(template.Flow) == ".js" && fileutil.FileExists(template.Flow) {
			// load file respecting sandbox
			file, err := options.Options.LoadHelperFile(template.Flow, options.TemplatePath, options.Catalog)
			if err != nil {
				return nil, errorutil.NewWithErr(err).Msgf("loading flow file from %v denied", template.Flow)
			}
			defer file.Close()
			if bin, err := io.ReadAll(file); err == nil {
				template.Flow = string(bin)
			} else {
				return nil, errorutil.NewWithErr(err).Msgf("something went wrong failed to read file")
			}
		}
		options.Flow = template.Flow
	}

	// create empty context args for template scope
	options.CreateTemplateCtxStore()
	options.ProtocolType = template.Type()
	options.Constants = template.Constants

	// initialize the js compiler if missing
	if options.JsCompiler == nil {
		options.JsCompiler = compiler.New()
	}

	template.Options = &options
	// If no requests, and it is also not a workflow, return error.
	if template.Requests() == 0 {
		return nil, fmt.Errorf("no requests defined for %s", template.ID)
	}

	if err := template.compileProtocolRequests(options); err != nil {
		return nil, err
	}

	if template.Executer != nil {
		if err := template.Executer.Compile(); err != nil {
			return nil, errors.Wrap(err, "could not compile request")
		}
		template.TotalRequests = template.Executer.Requests()
	}
	if template.Executer == nil && template.CompiledWorkflow == nil {
		return nil, ErrCreateTemplateExecutor
	}
	template.parseSelfContainedRequests()

	// check if the template is verified
	for _, verifier := range signer.DefaultVerifiers {
		if template.Verified {
			break
		}
		template.Verified, _ = signer.Verify(verifier, data)
	}

	return template, nil
}