package cabana

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"net/url"
	"strings"

	"git.golem15.com/golem15/summercms/modules/lagoon"
	"git.golem15.com/golem15/summercms/modules/pact"
	"git.golem15.com/golem15/summercms/modules/party"
	"git.golem15.com/golem15/summercms/modules/towel"
	"gorm.io/gorm"
)

// accountContributionCatalog holds the My account sections plugins
// contribute (pact.HasAccountContributions), in activation order.
type accountContributionCatalog struct {
	ordered []compiledAccountContribution
	byName  map[string]*compiledAccountContribution
}

// compiledAccountContribution is one contributed section with its owner.
type compiledAccountContribution struct {
	pluginID string
	section  pact.AccountContribution
	actions  map[string]pact.AccountAction
}

// compileAccountContributions collects pact.HasAccountContributions from
// plugins into reg, in activation order. Every failure stops boot with a
// message naming the plugin and the section: a name that is not an
// identifier, a name another plugin already contributed, an empty label, an
// action whose name is not an identifier or repeats within the section, a
// nil Run or an empty action label.
func compileAccountContributions(reg *Registry, plugins []party.Plugin) error {
	if reg == nil {
		return fmt.Errorf("cabana: registry is nil")
	}
	cat := &accountContributionCatalog{byName: map[string]*compiledAccountContribution{}}
	for _, plugin := range plugins {
		if plugin == nil {
			continue
		}
		src, ok := plugin.(pact.HasAccountContributions)
		if !ok || src == nil {
			continue
		}
		pluginID := plugin.ID()
		for _, section := range src.AccountContributions() {
			prefix := fmt.Sprintf("cabana: plugin %s contributes account section %q", pluginID, section.Name)
			if !identifier(section.Name) {
				return fmt.Errorf("%s: the name is not an identifier", prefix)
			}
			if taken, ok := cat.byName[section.Name]; ok {
				return fmt.Errorf("%s: plugin %s already contributes a section with that name", prefix, taken.pluginID)
			}
			if strings.TrimSpace(section.Label) == "" {
				return fmt.Errorf("%s: it needs a label", prefix)
			}
			compiled := &compiledAccountContribution{pluginID: pluginID, section: section, actions: map[string]pact.AccountAction{}}
			for _, action := range section.Actions {
				if !identifier(action.Name) {
					return fmt.Errorf("%s: action name %q is not an identifier", prefix, action.Name)
				}
				if _, dup := compiled.actions[action.Name]; dup {
					return fmt.Errorf("%s: duplicate action %q", prefix, action.Name)
				}
				if action.Run == nil {
					return fmt.Errorf("%s: action %q has no Run function", prefix, action.Name)
				}
				if strings.TrimSpace(action.Label) == "" {
					return fmt.Errorf("%s: action %q needs a label", prefix, action.Name)
				}
				compiled.actions[action.Name] = action
			}
			cat.ordered = append(cat.ordered, *compiled)
			cat.byName[section.Name] = &cat.ordered[len(cat.ordered)-1]
		}
	}
	// The slice may have grown: point the map at the final backing array.
	for i := range cat.ordered {
		cat.byName[cat.ordered[i].section.Name] = &cat.ordered[i]
	}
	reg.accountContributions = cat
	return nil
}

// accountContributionsList serves GET /account/contributions: every
// contributed section with its status for the signed-in administrator and
// the actions they may run that apply to them, labels translated. A
// section whose Status fails is sent with Error set and no status, and an
// action whose Applies fails is left out and sets Error on its section (the
// admin sees why a button is missing), both logged: one plugin's error never
// answers 500 for the list.
func (s *service) accountContributionsList(w http.ResponseWriter, r *http.Request) {
	principal := accountPrincipal(w, r)
	if principal == nil {
		return
	}
	ctx := r.Context()
	tr := s.translator()
	out := []AccountContributionView{}
	if s.reg != nil && s.reg.accountContributions != nil {
		for _, item := range s.reg.accountContributions.ordered {
			view := AccountContributionView{
				Name:        item.section.Name,
				Label:       translateKey(ctx, tr, item.section.Label),
				Description: translateKey(ctx, tr, item.section.Description),
				Actions:     []AccountContributionActionView{},
			}
			if item.section.Status != nil {
				// One plugin's failure never hides the other sections: the
				// section is sent with an empty status and the error flag.
				status, err := item.section.Status(ctx, principal.ID)
				if err != nil {
					moduleLog.ErrorContext(ctx, "cabana: account contribution status failed", "section", item.section.Name, "plugin", item.pluginID, "error", err)
					view.Error = true
				} else {
					view.Status = localizeDetail(ctx, tr, status)
				}
			}
			for _, action := range item.section.Actions {
				if !Allows(principal, action.Permissions) {
					continue
				}
				if action.Applies != nil {
					applies, err := action.Applies(ctx, principal.ID)
					if err != nil {
						// The action is left out and the section says so
						// (RB-IN-02); the other sections are still answered.
						moduleLog.ErrorContext(ctx, "cabana: account contribution applies failed", "section", item.section.Name, "action", action.Name, "plugin", item.pluginID, "error", err)
						view.Error = true
						continue
					}
					if !applies {
						continue
					}
				}
				view.Actions = append(view.Actions, AccountContributionActionView{
					Name:    action.Name,
					Label:   translateKey(ctx, tr, action.Label),
					Confirm: translateKey(ctx, tr, action.Confirm),
					Danger:  action.Danger,
				})
			}
			out = append(out, view)
		}
	}
	WriteData(w, http.StatusOK, out, map[string]any{})
}

// accountContributionAction serves POST /account/contributions/{name}/actions/{action}:
// an unknown section or action is 404, a missing permission 403, an action
// that no longer applies 409; then Run runs for the signed-in administrator
// inside a transaction when the admin has a database (the context carries
// it, as for record actions) and its message and URL are answered.
func (s *service) accountContributionAction(w http.ResponseWriter, r *http.Request) {
	principal := accountPrincipal(w, r)
	if principal == nil {
		return
	}
	var item *compiledAccountContribution
	if s.reg != nil && s.reg.accountContributions != nil {
		item = s.reg.accountContributions.byName[r.PathValue("name")]
	}
	if item == nil {
		WriteError(w, http.StatusNotFound, "not_found", msgNotFound)
		return
	}
	action, ok := item.actions[r.PathValue("action")]
	if !ok {
		WriteError(w, http.StatusNotFound, "not_found", msgNotFound)
		return
	}
	if !s.allowAction(w, r, action.Permissions) {
		return
	}
	tr := s.translator()
	ctx := towel.WithLocale(r.Context(), schemaLocale(r.Context(), tr))
	run := func(ctx context.Context) (pact.AccountActionResult, error) {
		if action.Applies != nil {
			applies, err := action.Applies(ctx, principal.ID)
			if err != nil {
				return pact.AccountActionResult{}, err
			}
			if !applies {
				return pact.AccountActionResult{}, actionConflict{}
			}
		}
		return action.Run(ctx, pact.AccountActionInput{AdminID: principal.ID})
	}
	var result pact.AccountActionResult
	var err error
	if db, dbErr := s.db(); dbErr == nil {
		err = lagoon.Transaction(ctx, db, func(ctx context.Context, tx *gorm.DB) error {
			result, err = run(withTx(ctx, tx))
			return err
		})
	} else {
		result, err = run(ctx)
	}
	if err != nil {
		// A refusal the plugin authored (403, 422) or a stale action (409)
		// is answered as is; anything else is the plugin's failure, logged
		// here and answered as an opaque 500.
		var stale actionConflict
		var refused *ForbiddenError
		var invalid *ValidationError
		if !errors.As(err, &stale) && !errors.As(err, &refused) && !errors.As(err, &invalid) {
			moduleLog.ErrorContext(ctx, "cabana: account contribution action failed", "section", item.section.Name, "action", action.Name, "plugin", item.pluginID, "error", err)
		}
		writeCRUDError(w, localizeControllerError(ctx, tr, err))
		return
	}
	moduleLog.InfoContext(ctx, "cabana: account contribution action", "admin_id", principal.ID, "section", item.section.Name, "action", action.Name)
	if result.URL != "" && !safeAccountActionURL(result.URL) {
		// Never log the URL itself: it may carry a secret or a script.
		moduleLog.ErrorContext(ctx, "cabana: account contribution action answered a non-http URL", "section", item.section.Name, "action", action.Name, "plugin", item.pluginID)
		result.URL = ""
	}
	WriteData(w, http.StatusOK, AccountActionResultView{
		Message: translateKey(ctx, tr, result.Message),
		URL:     result.URL,
	}, nil)
}

// safeAccountActionURL reports whether an account action's URL may be handed
// to the admin's browser, which renders it as a link and opens it: an
// absolute http or https URL with a host, or a same-origin relative path
// (exactly one leading "/", no scheme). Anything else, javascript: and data:
// included, is refused.
func safeAccountActionURL(raw string) bool {
	u, err := url.Parse(raw)
	if err != nil {
		return false
	}
	if u.Scheme == "" {
		return strings.HasPrefix(raw, "/") && !strings.HasPrefix(raw, "//") && !strings.HasPrefix(raw, "/\\") && u.Host == ""
	}
	return (u.Scheme == "https" || u.Scheme == "http") && u.Host != ""
}