package godog

import (
	"flag"
	"fmt"
	"os"
	"reflect"
	"regexp"
	"runtime"

	"github.com/DATA-DOG/godog/gherkin"
)

// Status represents a step or scenario status
type Status int

// step or scenario status constants
const (
	invalid Status = iota
	Passed
	Failed
	Undefined
)

// String represents status as string
func (s Status) String() string {
	switch s {
	case Passed:
		return "passed"
	case Failed:
		return "failed"
	case Undefined:
		return "undefined"
	}
	return "invalid"
}

// Objects implementing the StepHandler interface can be
// registered as step definitions in godog
//
// HandleStep method receives all arguments which
// will be matched according to the regular expression
// which is passed with a step registration.
// The error in return - represents a reason of failure.
//
// Returning signals that the step has finished
// and that the feature runner can move on to the next
// step.
type StepHandler interface {
	HandleStep(args ...*Arg) error
}

// StepHandlerFunc type is an adapter to allow the use of
// ordinary functions as Step handlers.  If f is a function
// with the appropriate signature, StepHandlerFunc(f) is a
// StepHandler object that calls f.
type StepHandlerFunc func(...*Arg) error

// HandleStep calls f(step_arguments...).
func (f StepHandlerFunc) HandleStep(args ...*Arg) error {
	return f(args...)
}

var errPending = fmt.Errorf("pending step")

type stepMatchHandler struct {
	handler StepHandler
	expr    *regexp.Regexp
}

// Suite is an interface which allows various contexts
// to register step definitions and event handlers
type Suite interface {
	Step(expr *regexp.Regexp, h StepHandler)
	// suite events
	BeforeSuite(h BeforeSuiteHandler)
	BeforeScenario(h BeforeScenarioHandler)
	BeforeStep(h BeforeStepHandler)
	AfterStep(h AfterStepHandler)
	AfterScenario(h AfterScenarioHandler)
	AfterSuite(h AfterSuiteHandler)
}

type suite struct {
	stepHandlers []*stepMatchHandler
	features     []*gherkin.Feature
	fmt          Formatter

	failed bool

	// suite event handlers
	beforeSuiteHandlers    []BeforeSuiteHandler
	beforeScenarioHandlers []BeforeScenarioHandler
	beforeStepHandlers     []BeforeStepHandler
	afterStepHandlers      []AfterStepHandler
	afterScenarioHandlers  []AfterScenarioHandler
	afterSuiteHandlers     []AfterSuiteHandler
}

// New initializes a suite which supports the Suite
// interface. The instance is passed around to all
// context initialization functions from *_test.go files
func New() *suite {
	return &suite{}
}

// Step allows to register a StepHandler in Godog
// feature suite, the handler will be applied to all
// steps matching the given regexp
//
// Note that if there are two handlers which may match
// the same step, then the only first matched handler
// will be applied
//
// If none of the StepHandlers are matched, then a pending
// step error will be raised.
func (s *suite) Step(expr *regexp.Regexp, h StepHandler) {
	s.stepHandlers = append(s.stepHandlers, &stepMatchHandler{
		handler: h,
		expr:    expr,
	})
}

// BeforeSuite registers a BeforeSuiteHandler
// to be run once before suite runner
func (s *suite) BeforeSuite(h BeforeSuiteHandler) {
	s.beforeSuiteHandlers = append(s.beforeSuiteHandlers, h)
}

// BeforeScenario registers a BeforeScenarioHandler
// to be run before every scenario
func (s *suite) BeforeScenario(h BeforeScenarioHandler) {
	s.beforeScenarioHandlers = append(s.beforeScenarioHandlers, h)
}

// BeforeStep registers a BeforeStepHandler
// to be run before every scenario
func (s *suite) BeforeStep(h BeforeStepHandler) {
	s.beforeStepHandlers = append(s.beforeStepHandlers, h)
}

// AfterStep registers an AfterStepHandler
// to be run after every scenario
func (s *suite) AfterStep(h AfterStepHandler) {
	s.afterStepHandlers = append(s.afterStepHandlers, h)
}

// AfterScenario registers an AfterScenarioHandler
// to be run after every scenario
func (s *suite) AfterScenario(h AfterScenarioHandler) {
	s.afterScenarioHandlers = append(s.afterScenarioHandlers, h)
}

// AfterSuite registers a AfterSuiteHandler
// to be run once after suite runner
func (s *suite) AfterSuite(h AfterSuiteHandler) {
	s.afterSuiteHandlers = append(s.afterSuiteHandlers, h)
}

// Run - runs a godog feature suite
func (s *suite) Run() {
	var err error
	if !flag.Parsed() {
		flag.Parse()
	}

	// check if we need to just show something first
	switch {
	case cfg.version:
		fmt.Println(cl("Godog", green) + " version is " + cl(Version, yellow))
		return
	case cfg.definitions:
		s.printStepDefinitions()
		return
	}

	// run a feature suite
	fatal(cfg.validate())
	s.fmt = cfg.formatter()
	s.features, err = cfg.features()
	fatal(err)

	s.run()

	if s.failed {
		os.Exit(1)
	}
}

func (s *suite) run() {
	// run before suite handlers
	for _, h := range s.beforeSuiteHandlers {
		h.HandleBeforeSuite()
	}
	// run features
	for _, f := range s.features {
		s.runFeature(f)
		if s.failed && cfg.stopOnFailure {
			// stop on first failure
			break
		}
	}
	// run after suite handlers
	for _, h := range s.afterSuiteHandlers {
		h.HandleAfterSuite()
	}
	s.fmt.Summary()
}

func (s *suite) runStep(step *gherkin.Step) (err error) {
	var match *stepMatchHandler
	var args []*Arg
	for _, h := range s.stepHandlers {
		if m := h.expr.FindStringSubmatch(step.Text); len(m) > 0 {
			match = h
			for _, a := range m[1:] {
				args = append(args, &Arg{value: a})
			}
			if step.Table != nil {
				args = append(args, &Arg{value: step.Table})
			}
			if step.PyString != nil {
				args = append(args, &Arg{value: step.PyString})
			}
			break
		}
	}
	if match == nil {
		s.fmt.Undefined(step)
		return errPending
	}

	defer func() {
		if e := recover(); e != nil {
			err = e.(error)
			s.fmt.Failed(step, match, err)
		}
	}()

	if err = match.handler.HandleStep(args...); err != nil {
		s.fmt.Failed(step, match, err)
	} else {
		s.fmt.Passed(step, match)
	}
	return
}

func (s *suite) runSteps(steps []*gherkin.Step) (st Status) {
	for _, step := range steps {
		if st == Failed || st == Undefined {
			s.fmt.Skipped(step)
			continue
		}

		// run before step handlers
		for _, h := range s.beforeStepHandlers {
			h.HandleBeforeStep(step)
		}

		err := s.runStep(step)
		switch err {
		case errPending:
			st = Undefined
		case nil:
			st = Passed
		default:
			st = Failed
		}

		// run after step handlers
		for _, h := range s.afterStepHandlers {
			h.HandleAfterStep(step, st)
		}
	}
	return
}

func (s *suite) skipSteps(steps []*gherkin.Step) {
	for _, step := range steps {
		s.fmt.Skipped(step)
	}
}

func (s *suite) runFeature(f *gherkin.Feature) {
	s.fmt.Node(f)
	for _, scenario := range f.Scenarios {
		var status Status

		// run before scenario handlers
		for _, h := range s.beforeScenarioHandlers {
			h.HandleBeforeScenario(scenario)
		}

		// background
		if f.Background != nil {
			s.fmt.Node(f.Background)
			status = s.runSteps(f.Background.Steps)
		}

		// scenario
		s.fmt.Node(scenario)
		switch {
		case status == Failed:
			s.skipSteps(scenario.Steps)
		case status == Undefined:
			s.skipSteps(scenario.Steps)
		case status == Passed || status == invalid:
			status = s.runSteps(scenario.Steps)
		}

		// run after scenario handlers
		for _, h := range s.afterScenarioHandlers {
			h.HandleAfterScenario(scenario, status)
		}

		if status == Failed {
			s.failed = true
			if cfg.stopOnFailure {
				return
			}
		}
	}
}

func (st *suite) printStepDefinitions() {
	var longest int
	for _, def := range st.stepHandlers {
		if longest < len(def.expr.String()) {
			longest = len(def.expr.String())
		}
	}
	for _, def := range st.stepHandlers {
		location := runtime.FuncForPC(reflect.ValueOf(def.handler).Pointer()).Name()
		fmt.Println(cl(def.expr.String(), yellow)+s(longest-len(def.expr.String())), cl("# "+location, black))
	}
	if len(st.stepHandlers) == 0 {
		fmt.Println("there were no contexts registered, could not find any step definition..")
	}
}