package plugins

import (
	"encoding/json"
	"log"
	"os"
	"path/filepath"

	lua "github.com/yuin/gopher-lua"
)

// Meta is the plugin.json descriptor.
type Meta struct {
	Name        string            `json:"name"`
	Version     string            `json:"version"`
	Description string            `json:"description,omitempty"`
	Author      string            `json:"author,omitempty"`
	Hooks       map[string]string `json:"hooks,omitempty"`
	UI          *UIContrib        `json:"ui,omitempty"`
	Background  []BackgroundTask  `json:"background_tasks,omitempty"`
	NodeTypes   []string          `json:"node_types,omitempty"`
	Panel       string            `json:"panel,omitempty"`
	Templates   []string          `json:"templates,omitempty"`
	Migrations  []string          `json:"migrations,omitempty"`
}

// UIContrib describes UI contributions from a plugin.
type UIContrib struct {
	SidebarItems  []SidebarItem  `json:"sidebar_items,omitempty"`
	NodeTabs      []NodeTab      `json:"node_tabs,omitempty"`
	NodeActions   []NodeAction   `json:"node_actions,omitempty"`
	SettingsPages []SettingsPage `json:"settings_pages,omitempty"`
}

// SidebarItem is a navigation item in the sidebar.
type SidebarItem struct {
	ID    string `json:"id"`
	Label string `json:"label"`
	Icon  string `json:"icon,omitempty"`
	Page  string `json:"page"`
}

// NodeTab is an extra tab in the node detail view.
type NodeTab struct {
	ID    string `json:"id"`
	Label string `json:"label"`
	Page  string `json:"page"`
}

// NodeAction is an action button in the node detail.
type NodeAction struct {
	ID    string `json:"id"`
	Label string `json:"label"`
	Icon  string `json:"icon,omitempty"`
	Page  string `json:"page,omitempty"`
}

// SettingsPage is a plugin settings page in the settings dialog.
type SettingsPage struct {
	ID    string `json:"id"`
	Label string `json:"label"`
	Page  string `json:"page"`
}

// BackgroundTask describes a recurring background task.
type BackgroundTask struct {
	ID       string `json:"id"`
	Interval string `json:"interval"` // e.g. "5m", "1h", "30s"
	Script   string `json:"script"`   // relative path to .lua file
}

// Plugin represents a loaded plugin with its runtime.
type Plugin struct {
	Meta    Meta
	Dir     string // absolute path to plugin directory
	DataDir string // .verstak/plugins/<name>/data — plugin's own SQLite storage
	Active  bool

	// Runtime (set after InitRuntime)
	vm        *LuaVM
	scheduler *Scheduler
}

// Manager discovers and loads plugins from .verstak/plugins/.
type Manager struct {
	vaultRoot string
	plugins   []Plugin

	// Services exposed to Lua plugin API
	Services *CoreServices
}

// NewManager creates a plugin manager for a vault.
func NewManager(vaultRoot string) *Manager {
	return &Manager{vaultRoot: vaultRoot}
}

// Discover scans .verstak/plugins/* for plugin.json files.
func (m *Manager) Discover() {
	pluginsDir := filepath.Join(m.vaultRoot, ".verstak", "plugins")
	entries, err := os.ReadDir(pluginsDir)
	if err != nil {
		return // no plugins dir — OK
	}

	for _, e := range entries {
		if !e.IsDir() {
			continue
		}
		metaPath := filepath.Join(pluginsDir, e.Name(), "plugin.json")
		data, err := os.ReadFile(metaPath)
		if err != nil {
			continue // no plugin.json — skip
		}
		var meta Meta
		if err := json.Unmarshal(data, &meta); err != nil {
			log.Printf("[plugins] %s: invalid plugin.json: %v", e.Name(), err)
			continue
		}
		if meta.Name == "" {
			meta.Name = e.Name()
		}
	dataDir := filepath.Join(pluginsDir, e.Name(), "data")
	os.MkdirAll(dataDir, 0o750)

	m.plugins = append(m.plugins, Plugin{
		Meta:    meta,
		Dir:     filepath.Join(pluginsDir, e.Name()),
		DataDir: dataDir,
		Active:  true,
	})
	}
}

// InitRuntimes creates Lua VMs and schedulers for all active plugins.
// Must be called after Discover() and before using plugins.
func (m *Manager) InitRuntimes() {
	for i := range m.plugins {
		if !m.plugins[i].Active {
			continue
		}
		p := &m.plugins[i]

		// Create Lua VM
		vm, err := NewLuaVM(p)
		if err != nil {
			log.Printf("[plugins] %s: failed to create Lua VM: %v", p.Meta.Name, err)
			p.Active = false
			continue
		}
		p.vm = vm
		if m.Services != nil {
			vm.SetServices(m.Services)
		}

		// Load main.lua if it exists
		mainPath := filepath.Join(p.Dir, "main.lua")
		if _, err := os.Stat(mainPath); err == nil {
			if err := vm.LoadScript("main.lua"); err != nil {
				log.Printf("[plugins] %s: failed to load main.lua: %v", p.Meta.Name, err)
			}
		}

		// Create scheduler
		p.scheduler = NewScheduler(p, vm)
		for _, bg := range p.Meta.Background {
			if err := p.scheduler.AddTask(bg); err != nil {
				log.Printf("[plugins] %s: failed to add task %s: %v", p.Meta.Name, bg.ID, err)
			}
		}
	}
}

// CallInitHooks calls on_init for all active plugins.
func (m *Manager) CallInitHooks() {
	for i := range m.plugins {
		if !m.plugins[i].Active {
			continue
		}
		p := &m.plugins[i]
		if hookName, ok := p.Meta.Hooks["on_init"]; ok && p.vm != nil {
			if err := p.vm.CallHook(hookName); err != nil {
				log.Printf("[plugins] %s: on_init error: %v", p.Meta.Name, err)
			}
		}
	}
}

// CallVaultOpenHooks calls on_vault_open for all active plugins.
func (m *Manager) CallVaultOpenHooks(vaultPath string) {
	for i := range m.plugins {
		if !m.plugins[i].Active {
			continue
		}
		p := &m.plugins[i]
		if hookName, ok := p.Meta.Hooks["on_vault_open"]; ok && p.vm != nil {
			if err := p.vm.CallHook(hookName, lua.LString(vaultPath)); err != nil {
				log.Printf("[plugins] %s: on_vault_open error: %v", p.Meta.Name, err)
			}
		}
	}
}

// StartSchedulers starts background tasks for all active plugins.
func (m *Manager) StartSchedulers() {
	for i := range m.plugins {
		if !m.plugins[i].Active {
			continue
		}
		p := &m.plugins[i]
		if p.scheduler != nil {
			p.scheduler.Start()
		}
	}
}

// StopSchedulers stops all background tasks.
func (m *Manager) StopSchedulers() {
	for i := range m.plugins {
		p := &m.plugins[i]
		if p.scheduler != nil {
			p.scheduler.Stop()
		}
	}
}

// CallShutdownHooks calls on_shutdown for all active plugins.
func (m *Manager) CallShutdownHooks() {
	for i := range m.plugins {
		if !m.plugins[i].Active {
			continue
		}
		p := &m.plugins[i]
		if hookName, ok := p.Meta.Hooks["on_shutdown"]; ok && p.vm != nil {
			if err := p.vm.CallHook(hookName); err != nil {
				log.Printf("[plugins] %s: on_shutdown error: %v", p.Meta.Name, err)
			}
		}
	}
}

// CloseRuntimes shuts down all Lua VMs.
func (m *Manager) CloseRuntimes() {
	for i := range m.plugins {
		p := &m.plugins[i]
		if p.vm != nil {
			p.vm.Close()
			p.vm = nil
		}
	}
}

// Plugins returns all discovered plugins.
func (m *Manager) Plugins() []Plugin {
	return m.plugins
}

// Active returns only active plugins.
func (m *Manager) Active() []Plugin {
	var out []Plugin
	for _, p := range m.plugins {
		if p.Active {
			out = append(out, p)
		}
	}
	return out
}

// Templates returns all templates from active plugins.
func (m *Manager) Templates() []TemplateDefinition {
	var out []TemplateDefinition
	// Plugin templates.
	for _, p := range m.Active() {
		for _, tmplName := range p.Meta.Templates {
			tmplPath := filepath.Join(p.Dir, "templates", tmplName+".json")
			data, err := os.ReadFile(tmplPath)
			if err != nil {
				continue
			}
			var tmpl TemplateDefinition
			if err := json.Unmarshal(data, &tmpl); err != nil {
				continue
			}
			if tmpl.Name == "" {
				tmpl.Name = tmplName
			}
			tmpl.Plugin = p.Meta.Name
			out = append(out, tmpl)
		}
	}
	return out
}

// TemplateDefinition describes a predefined tree of nodes.
type TemplateDefinition struct {
	Name        string     `json:"name"`
	Description string     `json:"description,omitempty"`
	Icon        string     `json:"icon,omitempty"`
	Plugin      string     // source plugin name
	RootType    string     `json:"root_type"`
	Tree        []TreeNode `json:"tree"`
	Meta        []NodeMeta `json:"meta,omitempty"`
}

// TreeNode is a single item in a template tree.
type TreeNode struct {
	Type     string     `json:"type"`
	Title    string     `json:"title"`
	Slug     string     `json:"slug,omitempty"`
	Children []TreeNode `json:"children,omitempty"`
}

// NodeMeta is key-value metadata for the root node.
type NodeMeta struct {
	Key   string `json:"key"`
	Label string `json:"label"`
	Type  string `json:"type"` // text, url, etc.
}

// Enable activates a plugin by name.
func (m *Manager) Enable(name string) {
	for i := range m.plugins {
		if m.plugins[i].Meta.Name == name {
			m.plugins[i].Active = true
			return
		}
	}
}

// Disable deactivates a plugin by name.
func (m *Manager) Disable(name string) {
	for i := range m.plugins {
		if m.plugins[i].Meta.Name == name {
			m.plugins[i].Active = false
			return
		}
	}
}

// ActiveNames returns names of active plugins.
func (m *Manager) ActiveNames() []string {
	var out []string
	for _, p := range m.Active() {
		out = append(out, p.Meta.Name)
	}
	return out
}

// MigrationFiles returns paths to SQL migration files from active plugins.
func (m *Manager) MigrationFiles() []string {
	var out []string
	for _, p := range m.Active() {
		for _, mig := range p.Meta.Migrations {
			path := filepath.Join(p.Dir, "migrations", mig)
			if _, err := os.Stat(path); err == nil {
				out = append(out, path)
			}
		}
	}
	return out
}