package plugin

import (
	"context"
	"path/filepath"
	"plugin"
	"sync"

	"github.com/pkg/errors"
)

type Registry struct {
	plugins map[string]Plugin
	mutex   sync.RWMutex
}

func (r *Registry) Add(plg Plugin) {
	r.mutex.Lock()
	defer r.mutex.Unlock()

	r.plugins[plg.PluginName()] = plg
}

func (r *Registry) Get(name string) (Plugin, error) {
	r.mutex.RLock()
	defer r.mutex.RUnlock()

	plg, exists := r.plugins[name]
	if !exists {
		return nil, errors.WithStack(ErrPluginNotFound)
	}

	return plg, nil
}

func (r *Registry) Load(ctx context.Context, path string) (Plugin, error) {
	p, err := plugin.Open(path)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	registerFuncSymbol, err := p.Lookup("RegisterPlugin")
	if err != nil {
		return nil, errors.WithStack(err)
	}

	register, ok := registerFuncSymbol.(func(context.Context) (Plugin, error))
	if !ok {
		return nil, errors.WithStack(ErrInvalidRegisterFunc)
	}

	plg, err := register(ctx)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	if plg == nil {
		return nil, errors.WithStack(ErrInvalidPlugin)
	}

	r.Add(plg)

	return plg, nil
}

func (r *Registry) LoadAll(ctx context.Context, pattern string) ([]Plugin, error) {
	extensions := make([]Plugin, 0)

	matches, err := filepath.Glob(pattern)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	for _, m := range matches {
		ext, err := r.Load(ctx, m)
		if err != nil {
			return nil, errors.WithStack(err)
		}

		extensions = append(extensions, ext)
	}

	return extensions, nil
}

func (r *Registry) Plugins() []Plugin {
	r.mutex.RLock()
	defer r.mutex.RUnlock()

	plugins := make([]Plugin, 0, len(r.plugins))
	for _, p := range r.plugins {
		plugins = append(plugins, p)
	}

	return plugins
}

type IteratorFunc func(plg Plugin) error

func (r *Registry) Each(iterator IteratorFunc) error {
	r.mutex.RLock()
	defer r.mutex.RUnlock()

	for _, p := range r.plugins {
		if err := iterator(p); err != nil {
			return errors.WithStack(err)
		}
	}

	return nil
}

func NewRegistry() *Registry {
	return &Registry{
		plugins: make(map[string]Plugin),
	}
}