// Package plugin implements functions and types for maintaining and running
// stash plugins.
//
// Stash plugins are configured using yml files in the configured plugins
// directory. These yml files must follow the Config structure format.
//
// The main entry into the plugin sub-system is via the Cache type.
package plugin

import (
	"context"
	"fmt"
	"net/http"
	"os"
	"path/filepath"
	"strconv"

	"github.com/stashapp/stash/pkg/logger"
	"github.com/stashapp/stash/pkg/models"
	"github.com/stashapp/stash/pkg/plugin/common"
	"github.com/stashapp/stash/pkg/session"
	"github.com/stashapp/stash/pkg/sliceutil/stringslice"
)

type Plugin struct {
	ID          string        `json:"id"`
	Name        string        `json:"name"`
	Description *string       `json:"description"`
	URL         *string       `json:"url"`
	Version     *string       `json:"version"`
	Tasks       []*PluginTask `json:"tasks"`
	Hooks       []*PluginHook `json:"hooks"`
}

type ServerConfig interface {
	GetHost() string
	GetPort() int
	GetConfigPath() string
	HasTLSConfig() bool
	GetPluginsPath() string
	GetPythonPath() string
}

// Cache stores plugin details.
type Cache struct {
	config       ServerConfig
	plugins      []Config
	sessionStore *session.Store
	gqlHandler   http.Handler
}

// NewCache returns a new Cache.
//
// Plugins configurations are loaded from yml files in the plugin
// directory in the config and any subdirectories.
//
// Does not load plugins. Plugins will need to be
// loaded explicitly using ReloadPlugins.
func NewCache(config ServerConfig) *Cache {
	return &Cache{
		config: config,
	}
}

func (c *Cache) RegisterGQLHandler(handler http.Handler) {
	c.gqlHandler = handler
}

func (c *Cache) RegisterSessionStore(sessionStore *session.Store) {
	c.sessionStore = sessionStore
}

// LoadPlugins clears the plugin cache and loads from the plugin path.
// In the event of an error during loading, the cache will be left empty.
func (c *Cache) LoadPlugins() error {
	c.plugins = nil
	plugins, err := loadPlugins(c.config.GetPluginsPath())
	if err != nil {
		return err
	}

	c.plugins = plugins
	return nil
}

func loadPlugins(path string) ([]Config, error) {
	plugins := make([]Config, 0)

	logger.Debugf("Reading plugin configs from %s", path)
	pluginFiles := []string{}
	err := filepath.Walk(path, func(fp string, f os.FileInfo, err error) error {
		if filepath.Ext(fp) == ".yml" {
			pluginFiles = append(pluginFiles, fp)
		}
		return nil
	})

	if err != nil {

		return nil, err
	}

	for _, file := range pluginFiles {
		plugin, err := loadPluginFromYAMLFile(file)
		if err != nil {
			logger.Errorf("Error loading plugin %s: %s", file, err.Error())
		} else {
			plugins = append(plugins, *plugin)
		}
	}

	return plugins, nil
}

// ListPlugins returns plugin details for all of the loaded plugins.
func (c Cache) ListPlugins() []*Plugin {
	var ret []*Plugin
	for _, s := range c.plugins {
		ret = append(ret, s.toPlugin())
	}

	return ret
}

// ListPluginTasks returns all runnable plugin tasks in all loaded plugins.
func (c Cache) ListPluginTasks() []*PluginTask {
	var ret []*PluginTask
	for _, s := range c.plugins {
		ret = append(ret, s.getPluginTasks(true)...)
	}

	return ret
}

func buildPluginInput(plugin *Config, operation *OperationConfig, serverConnection common.StashServerConnection, args []*PluginArgInput) common.PluginInput {
	args = applyDefaultArgs(args, operation.DefaultArgs)
	serverConnection.PluginDir = plugin.getConfigPath()
	return common.PluginInput{
		ServerConnection: serverConnection,
		Args:             toPluginArgs(args),
	}
}

func (c Cache) makeServerConnection(ctx context.Context) common.StashServerConnection {
	cookie := c.sessionStore.MakePluginCookie(ctx)

	serverConnection := common.StashServerConnection{
		Scheme:        "http",
		Host:          c.config.GetHost(),
		Port:          c.config.GetPort(),
		SessionCookie: cookie,
		Dir:           c.config.GetConfigPath(),
	}

	if c.config.HasTLSConfig() {
		serverConnection.Scheme = "https"
	}

	return serverConnection
}

// CreateTask runs the plugin operation for the pluginID and operation
// name provided. Returns an error if the plugin or the operation could not be
// resolved.
func (c Cache) CreateTask(ctx context.Context, pluginID string, operationName string, args []*PluginArgInput, progress chan float64) (Task, error) {
	serverConnection := c.makeServerConnection(ctx)

	// find the plugin and operation
	plugin := c.getPlugin(pluginID)

	if plugin == nil {
		return nil, fmt.Errorf("no plugin with ID %s", pluginID)
	}

	operation := plugin.getTask(operationName)
	if operation == nil {
		return nil, fmt.Errorf("no task with name %s in plugin %s", operationName, plugin.getName())
	}

	task := pluginTask{
		plugin:       plugin,
		operation:    operation,
		input:        buildPluginInput(plugin, operation, serverConnection, args),
		progress:     progress,
		gqlHandler:   c.gqlHandler,
		serverConfig: c.config,
	}
	return task.createTask(), nil
}

func (c Cache) ExecutePostHooks(ctx context.Context, id int, hookType HookTriggerEnum, input interface{}, inputFields []string) {
	if err := c.executePostHooks(ctx, hookType, common.HookContext{
		ID:          id,
		Type:        hookType.String(),
		Input:       input,
		InputFields: inputFields,
	}); err != nil {
		logger.Errorf("error executing post hooks: %s", err.Error())
	}
}

func (c Cache) ExecuteSceneUpdatePostHooks(ctx context.Context, input models.SceneUpdateInput, inputFields []string) {
	id, err := strconv.Atoi(input.ID)
	if err != nil {
		logger.Errorf("error converting id in SceneUpdatePostHooks: %v", err)
		return
	}
	c.ExecutePostHooks(ctx, id, SceneUpdatePost, input, inputFields)
}

func (c Cache) executePostHooks(ctx context.Context, hookType HookTriggerEnum, hookContext common.HookContext) error {
	visitedPlugins := session.GetVisitedPlugins(ctx)

	for _, p := range c.plugins {
		hooks := p.getHooks(hookType)
		// don't revisit a plugin we've already visited
		// only log if there's hooks that we're skipping
		if len(hooks) > 0 && stringslice.StrInclude(visitedPlugins, p.id) {
			logger.Debugf("plugin ID '%s' already triggered, not re-triggering", p.id)
			continue
		}

		for _, h := range hooks {
			newCtx := session.AddVisitedPlugin(ctx, p.id)
			serverConnection := c.makeServerConnection(newCtx)

			pluginInput := buildPluginInput(&p, &h.OperationConfig, serverConnection, nil)
			addHookContext(pluginInput.Args, hookContext)

			pt := pluginTask{
				plugin:       &p,
				operation:    &h.OperationConfig,
				input:        pluginInput,
				gqlHandler:   c.gqlHandler,
				serverConfig: c.config,
			}

			task := pt.createTask()
			if err := task.Start(); err != nil {
				return err
			}

			// handle cancel from context
			c := make(chan struct{})
			go func() {
				task.Wait()
				close(c)
			}()

			select {
			case <-ctx.Done():
				if err := task.Stop(); err != nil {
					logger.Warnf("could not stop task: %v", err)
				}
				return fmt.Errorf("operation cancelled")
			case <-c:
				// task finished normally
			}

			output := task.GetResult()
			if output == nil {
				logger.Debugf("%s [%s]: returned no result", hookType.String(), p.Name)
			} else {
				if output.Error != nil {
					logger.Errorf("%s [%s]: returned error: %s", hookType.String(), p.Name, *output.Error)
				} else if output.Output != nil {
					logger.Debugf("%s [%s]: returned: %v", hookType.String(), p.Name, output.Output)
				}
			}
		}
	}

	return nil
}

func (c Cache) getPlugin(pluginID string) *Config {
	for _, s := range c.plugins {
		if s.id == pluginID {
			return &s
		}
	}

	return nil
}