package container

import (
	"fmt"
	"os"
	"reflect"

	"github.com/pkg/errors"
)

// Option is a functional option for a container.
type Option interface {
	applyConfig(*config) error
	applyContainer(*container) error
}

// Provide creates a container option which registers the provided dependency
// injection constructors. Each constructor will be called at most once with the
// exception of scoped constructors which are called at most once per scope
// (see Scope).
func Provide(constructors ...interface{}) Option {
	return containerOption(func(ctr *container) error {
		return provide(ctr, nil, constructors)
	})
}

// ProvideWithScope creates a container option which registers the provided dependency
// injection constructors that are to be run in the provided scope. Each constructor
// will be called at most once.
func ProvideWithScope(scopeName string, constructors ...interface{}) Option {
	return containerOption(func(ctr *container) error {
		if scopeName == "" {
			return errors.Errorf("expected non-empty scope name")
		}

		return provide(ctr, ctr.createOrGetScope(scopeName), constructors)
	})
}

func provide(ctr *container, scope Scope, constructors []interface{}) error {
	for _, c := range constructors {
		rc, err := ExtractProviderDescriptor(c)
		if err != nil {
			return errors.WithStack(err)
		}
		_, err = ctr.addNode(&rc, scope)
		if err != nil {
			return errors.WithStack(err)
		}
	}
	return nil
}

func Supply(values ...interface{}) Option {
	loc := LocationFromCaller(1)
	return containerOption(func(ctr *container) error {
		for _, v := range values {
			err := ctr.supply(reflect.ValueOf(v), loc)
			if err != nil {
				return errors.WithStack(err)
			}
		}
		return nil
	})
}

// Logger creates an option which provides a logger function which will
// receive all log messages from the container.
func Logger(logger func(string)) Option {
	return configOption(func(c *config) error {
		logger("Initializing logger")
		c.loggers = append(c.loggers, logger)
		return nil
	})
}

func StdoutLogger() Option {
	return Logger(func(s string) {
		_, _ = fmt.Fprintln(os.Stdout, s)
	})
}

// Visualizer creates an option which provides a visualizer function which
// will receive a rendering of the container in the Graphiz DOT format
// whenever the container finishes building or fails due to an error. The
// graph is color-coded to aid debugging.
func Visualizer(visualizer func(dotGraph string)) Option {
	return configOption(func(c *config) error {
		c.addFuncVisualizer(visualizer)
		return nil
	})
}

func LogVisualizer() Option {
	return configOption(func(c *config) error {
		c.enableLogVisualizer()
		return nil
	})
}

func FileVisualizer(filename, format string) Option {
	return configOption(func(c *config) error {
		c.addFileVisualizer(filename, format)
		return nil
	})
}

func Debug() Option {
	return Options(
		StdoutLogger(),
		LogVisualizer(),
		FileVisualizer("container_dump.svg", "svg"),
	)
}

// Error creates an option which causes the dependency injection container to
// fail immediately.
func Error(err error) Option {
	return configOption(func(*config) error {
		return errors.WithStack(err)
	})
}

// Options creates an option which bundles together other options.
func Options(opts ...Option) Option {
	return option{
		configOption: func(cfg *config) error {
			for _, opt := range opts {
				err := opt.applyConfig(cfg)
				if err != nil {
					return errors.WithStack(err)
				}
			}
			return nil
		},
		containerOption: func(ctr *container) error {
			for _, opt := range opts {
				err := opt.applyContainer(ctr)
				if err != nil {
					return errors.WithStack(err)
				}
			}
			return nil
		},
	}
}

type configOption func(*config) error

func (c configOption) applyConfig(cfg *config) error {
	return c(cfg)
}

func (c configOption) applyContainer(*container) error {
	return nil
}

type containerOption func(*container) error

func (c containerOption) applyConfig(*config) error {
	return nil
}

func (c containerOption) applyContainer(ctr *container) error {
	return c(ctr)
}

type option struct {
	configOption
	containerOption
}

func (o option) applyConfig(c *config) error {
	return o.configOption(c)
}

func (o option) applyContainer(c *container) error {
	return o.containerOption(c)
}

var _, _, _ Option = (*configOption)(nil), (*containerOption)(nil), option{}