package cabana

import (
	"fmt"
	"strings"

	"git.golem15.com/golem15/summercms/modules/pact"
	"git.golem15.com/golem15/summercms/modules/party"
)

type controllerRef struct {
	plugin party.Plugin
	ctl    pact.AdminController
}

func collectControllers(plugins []party.Plugin) ([]controllerRef, error) {
	var out []controllerRef
	for _, p := range plugins {
		src, ok := p.(pact.HasAdminControllers)
		if !ok || p == nil {
			continue
		}
		for _, ctl := range src.AdminControllers() {
			if ctl == nil {
				continue
			}
			id := ctl.ID()
			if id != p.ID() && !strings.HasPrefix(id, p.ID()+".") {
				return nil, fmt.Errorf("cabana: controller %s is not owned by plugin %s", id, p.ID())
			}
			out = append(out, controllerRef{plugin: p, ctl: ctl})
		}
	}
	return out, nil
}

// reservedVendorSegments are the first path segments under the admin prefix
// that the SPA and API own. A controller ID maps to /{vendor}/{plugin}/..., so
// a vendor with one of these names would collide with them.
var reservedVendorSegments = map[string]bool{"api": true, "assets": true, "login": true, "settings": true}

func checkReservedSegments(items []controllerRef) error {
	for _, item := range items {
		id := item.ctl.ID()
		vendor, _, _ := strings.Cut(id, ".")
		if reservedVendorSegments[vendor] {
			return fmt.Errorf("cabana: controller %s uses the reserved admin path segment %q (reserved: api, assets, login, settings)", id, vendor)
		}
	}
	return nil
}

func compileRegistry(items []controllerRef) (*Registry, error) {
	byID := make(map[string]*CompiledController, len(items))
	assets := map[string]*pluginAsset{}
	for _, item := range items {
		id := item.ctl.ID()
		if _, exists := byID[id]; exists {
			return nil, fmt.Errorf("cabana: duplicate admin controller %s", id)
		}
		fsys, ok := item.plugin.(pact.AdminAssets)
		if !ok || fsys == nil || fsys.AdminFS() == nil {
			return nil, fmt.Errorf("cabana: plugin %s has admin controllers but no AdminFS", item.plugin.ID())
		}
		list, err := compileList(item.plugin.ID(), item.ctl, fsys.AdminFS())
		if err != nil {
			return nil, err
		}
		form, err := compileFormIfPresent(item.plugin.ID(), item.ctl, fsys.AdminFS())
		if err != nil {
			return nil, err
		}
		relations, err := compileRelations(item.plugin.ID(), item.ctl, fsys.AdminFS(), form)
		if err != nil {
			return nil, err
		}
		fieldRelations, err := compileFieldRelations(item.plugin.ID(), item.ctl, form)
		if err != nil {
			return nil, err
		}
		if form == nil && list != nil {
			// Without a compiled form there is nothing to create (D-14).
			list.ToolbarButtons = withoutAction(list.ToolbarButtons, "create")
		}
		compiled := &CompiledController{
			PluginID:       item.plugin.ID(),
			Controller:     item.ctl,
			List:           list,
			Form:           form,
			Relations:      relations,
			FieldRelations: fieldRelations,
		}
		if err := BindWritableFields(compiled); err != nil {
			return nil, err
		}
		if err := compileExtension(item.plugin.ID(), compiled, fsys.AdminFS()); err != nil {
			return nil, err
		}
		// Two controllers of one plugin declaring the same file share an entry.
		for _, file := range append(append([]*pluginAsset(nil), compiled.scripts...), compiled.styles...) {
			if _, exists := assets[file.key]; !exists {
				assets[file.key] = file
			}
		}
		byID[id] = compiled
	}
	return &Registry{byID: byID, assets: assets}, nil
}

func withoutAction(actions []string, drop string) []string {
	out := make([]string, 0, len(actions))
	for _, action := range actions {
		if action != drop {
			out = append(out, action)
		}
	}
	return out
}

func compileContributions(reg *Registry, plugins []party.Plugin) error {
	if reg == nil {
		return fmt.Errorf("cabana: registry is nil")
	}
	reg.permissions = map[string]pact.Permission{}
	reg.roleGrants = map[string]map[string]bool{}
	reg.settings = map[string]*CompiledSetting{}
	seenNavigation := map[string]struct{}{}

	for _, plugin := range plugins {
		if plugin == nil {
			continue
		}
		if src, ok := plugin.(pact.HasPermissions); ok && src != nil {
			for _, permission := range src.Permissions() {
				if !permissionCode(permission.Code, false) {
					return fmt.Errorf("cabana: plugin %s registered invalid permission %q", plugin.ID(), permission.Code)
				}
				if _, exists := reg.permissions[permission.Code]; exists {
					return fmt.Errorf("cabana: duplicate permission %s", permission.Code)
				}
				reg.permissions[permission.Code] = permission
				for _, role := range permission.Roles {
					role = strings.TrimSpace(role)
					if role == "" {
						return fmt.Errorf("cabana: permission %s has an empty role", permission.Code)
					}
					if reg.roleGrants[role] == nil {
						reg.roleGrants[role] = map[string]bool{}
					}
					reg.roleGrants[role][permission.Code] = true
				}
			}
		}
		if src, ok := plugin.(pact.HasSettings); ok && src != nil {
			assets, hasAssets := plugin.(pact.AdminAssets)
			for _, item := range src.Settings() {
				if !identifier(item.Code) {
					return fmt.Errorf("cabana: plugin %s registered invalid setting %q", plugin.ID(), item.Code)
				}
				if _, exists := reg.settings[item.Code]; exists {
					return fmt.Errorf("cabana: duplicate setting %s", item.Code)
				}
				if !hasAssets || assets == nil || assets.AdminFS() == nil {
					return fmt.Errorf("cabana: plugin %s has settings but no AdminFS", plugin.ID())
				}
				compiled, err := compileSetting(plugin.ID(), item, assets.AdminFS())
				if err != nil {
					return err
				}
				reg.settings[item.Code] = compiled
			}
		}
		if src, ok := plugin.(pact.HasNavigation); ok && src != nil {
			for _, item := range src.Navigation() {
				if err := validateNavigationShape(plugin.ID(), item, seenNavigation); err != nil {
					return err
				}
				reg.navigation = append(reg.navigation, item)
			}
		}
	}

	for id, controller := range reg.byID {
		if err := reg.validatePermissions("controller "+id, requiredOf(controller.Controller)); err != nil {
			return err
		}
		for name, relation := range controller.Relations {
			if err := reg.validatePermissions("relation "+id+"."+name, relation.RequiredPermissions); err != nil {
				return err
			}
		}
		for name, action := range controller.Actions {
			if err := reg.validatePermissions("action "+id+"."+name, action.Permissions); err != nil {
				return err
			}
		}
	}
	for _, item := range reg.navigation {
		if err := reg.validateNavigation(item); err != nil {
			return err
		}
	}
	for code, setting := range reg.settings {
		if err := reg.validatePermissions("setting "+code, setting.Item.Permissions); err != nil {
			return err
		}
	}
	return nil
}

func permissionCode(code string, wildcard bool) bool {
	parts := strings.Split(code, ".")
	if len(parts) < 2 {
		return false
	}
	for i, part := range parts {
		if wildcard && i == len(parts)-1 && part == "*" {
			return true
		}
		if !identifier(part) {
			return false
		}
	}
	return true
}

func (r *Registry) validatePermissions(owner string, permissions []string) error {
	for _, code := range permissions {
		if !permissionCode(code, true) || !r.permissionExists(code) {
			return fmt.Errorf("cabana: %s references unknown permission %s", owner, code)
		}
	}
	return nil
}

func (r *Registry) permissionExists(code string) bool {
	if r == nil {
		return false
	}
	if _, ok := r.permissions[code]; ok {
		return true
	}
	if !strings.HasSuffix(code, ".*") {
		return false
	}
	prefix := strings.TrimSuffix(code, "*")
	for candidate := range r.permissions {
		if strings.HasPrefix(candidate, prefix) {
			return true
		}
	}
	return false
}

func validateNavigationShape(pluginID string, item pact.NavigationItem, seen map[string]struct{}) error {
	if !identifier(item.Code) {
		return fmt.Errorf("cabana: plugin %s registered invalid navigation code %q", pluginID, item.Code)
	}
	if _, exists := seen[item.Code]; exists {
		return fmt.Errorf("cabana: duplicate navigation code %s", item.Code)
	}
	seen[item.Code] = struct{}{}
	childSeen := map[string]struct{}{}
	for _, child := range item.SideMenu {
		if !identifier(child.Code) {
			return fmt.Errorf("cabana: navigation %s has invalid child code %q", item.Code, child.Code)
		}
		if _, exists := childSeen[child.Code]; exists {
			return fmt.Errorf("cabana: navigation %s has duplicate child %s", item.Code, child.Code)
		}
		childSeen[child.Code] = struct{}{}
	}
	return nil
}

func (r *Registry) validateNavigation(item pact.NavigationItem) error {
	if _, ok := r.byID[item.Controller]; !ok {
		return fmt.Errorf("cabana: navigation %s references unknown controller %s", item.Code, item.Controller)
	}
	if err := r.validatePermissions("navigation "+item.Code, item.Permissions); err != nil {
		return err
	}
	for _, child := range item.SideMenu {
		if _, ok := r.byID[child.Controller]; !ok {
			return fmt.Errorf("cabana: navigation %s.%s references unknown controller %s", item.Code, child.Code, child.Controller)
		}
		if err := r.validatePermissions("navigation "+item.Code+"."+child.Code, child.Permissions); err != nil {
			return err
		}
	}
	return nil
}

func (r *Registry) rolePermissions(role string) map[string]bool {
	out := map[string]bool{}
	if r == nil {
		return out
	}
	for code, allowed := range r.roleGrants[role] {
		if allowed {
			out[code] = true
		}
	}
	return out
}