// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Commercial
// SPDX-FileCopyrightText: 2025-2026 Christian Galo

package web

import (
	"bytes"
	"database/sql"
	"encoding/json"
	"fmt"
	"html/template"
	"io/fs"
	"log/slog"
	"net/http"

	"git.coopcloud.tech/wiki-cafe/member-console/internal/auth"
	"git.coopcloud.tech/wiki-cafe/member-console/internal/config"
	"git.coopcloud.tech/wiki-cafe/member-console/internal/embeds"
	"git.coopcloud.tech/wiki-cafe/member-console/internal/forms"
	dcclient "git.coopcloud.tech/wiki-cafe/member-console/internal/integrations/discourse/client"
	dcmod "git.coopcloud.tech/wiki-cafe/member-console/internal/integrations/discourse/store"
	"git.coopcloud.tech/wiki-cafe/member-console/internal/server"
	"git.coopcloud.tech/wiki-cafe/member-console/internal/web"
	"git.coopcloud.tech/wiki-cafe/member-console/internal/workflows"
	temporalsdk "go.temporal.io/sdk/client"
)

// groupMappingConstraints translates this form's plausible constraint
// violations (docs/operator-ux-conventions.md §6 — names live next to the
// form they belong to).
var groupMappingConstraints = web.ConstraintMessages{
	"uq_group_mappings_group_name":   {Field: "group_name", Message: "That group is already managed by another mapping."},
	"fk_group_mappings_resource_key": {Field: "resource_key", Message: "Unknown resource key."},
}

// MappingViewModel is one entitlement→group mapping row.
type MappingViewModel struct {
	MappingID   string
	ResourceKey string
	// DisplayName is the resource key's friendly name, from the same
	// resource-key catalog the mapping-form picker uses, so the mappings
	// table leads with it instead of the raw key (ui-vocabulary 4.3).
	DisplayName string
	GroupName   string
	GroupID     int64
	CreatedAt   string
	DeleteURL   string
}

// UnlinkedPersonViewModel is one entitled-but-unlinked person.
type UnlinkedPersonViewModel struct {
	DisplayName string
	Email       string
}

// ConflictViewModel is one conflicted link.
type ConflictViewModel struct {
	DiscourseUsername string
	PersonID          string
}

// ResourceKeyOption is a select option for the mapping form.
type ResourceKeyOption struct {
	Key         string
	DisplayName string
}

// OperatorPageData is the discourse_operator.html body payload.
type OperatorPageData struct {
	Configured bool
	// Description, when the provider manifest declares one, overrides the
	// page header's default lead (operator-panel-navigation: "A provider
	// page leads with the integration's description").
	Description string

	// Sync health (latest sweep execution, from Temporal).
	SweepStatus string
	SweepTime   string

	Mappings     []MappingViewModel
	ResourceKeys []ResourceKeyOption
	Unlinked     []UnlinkedPersonViewModel
	Conflicts    []ConflictViewModel

	// Form is the mapping declaration, unbound on a plain render or bound
	// to a refused submission of it (form-library).
	Form forms.FormView

	Error string
}

// DiscourseOperatorHandler serves the Discourse integration's operator
// surface: entitlement→group mapping management and link/sync visibility
// (spec: discourse-operator-surface).
type DiscourseOperatorHandler struct {
	db              *sql.DB
	logger          *slog.Logger
	authConfig      *auth.Config
	apiClient       *dcclient.Client
	temporal        temporalsdk.Client
	configured      bool
	description     string
	sweepScheduleID string
	templates       *server.SafeTemplates
}

// DiscourseOperatorHandlerConfig configures the handler.
type DiscourseOperatorHandlerConfig struct {
	DB         *sql.DB
	Logger     *slog.Logger
	AuthConfig *auth.Config
	// Client is nil when the integration is unconfigured (the page then
	// renders only the unconfigured notice; mutation routes are unmounted).
	Client     *dcclient.Client
	Temporal   temporalsdk.Client
	Configured bool
	// Description: see OperatorPageData.Description.
	Description string
	// TemplatesFS is the integration's own template tree, injected by the
	// adapter (same cycle argument as FedWiki's operator handler).
	TemplatesFS fs.FS
	// SweepScheduleID names the sweep SCHEDULE to report health from
	// (this integration's workflows.SyncScheduleID; injected so this
	// package needs no import of its own workflows package). Runs are
	// resolved through the schedule because schedule-spawned executions
	// get timestamp-suffixed workflow IDs — see
	// workflows.ScheduleRunStatus.
	SweepScheduleID string
}

// NewDiscourseOperatorHandler composes the operator shell with the
// integration's body partial.
func NewDiscourseOperatorHandler(cfg DiscourseOperatorHandlerConfig) (*DiscourseOperatorHandler, error) {
	shellFS, err := fs.Sub(embeds.Templates, "templates")
	if err != nil {
		return nil, err
	}
	var tmpl *template.Template
	tmpl = template.New("discourse-operator").Funcs(template.FuncMap{
		"renderBody": func(name string, data any) (template.HTML, error) {
			var buf bytes.Buffer
			if err := tmpl.ExecuteTemplate(&buf, name, data); err != nil {
				return "", err
			}
			return template.HTML(buf.String()), nil
		},
		"deploymentName": config.DeploymentName,
		// The shell's <title> names the page (server.PageTitle).
		"pageTitle": server.PageTitle,
	})
	// The shell's landing branch references operator_lookup_result.html;
	// html/template's escape analysis requires every referenced template to
	// be in the set even though BodyTemplate pages never execute that
	// branch — parse it alongside the shell (core's operator.go does the
	// same; FedWiki's operator handler omits it and 500s — findings.md #8).
	tmpl, err = tmpl.ParseFS(shellFS, "operator.html", "partials/operator_lookup_result.html", "partials/operator_setup.html")
	if err != nil {
		return nil, err
	}
	if tmpl, err = web.ParseUIPartials(tmpl); err != nil {
		return nil, err
	}
	// An integration's operator page is an operator page: its trail is
	// rooted at the operator surface like every other (design D18).
	tmpl = tmpl.Funcs(template.FuncMap{"surfaceRoot": web.OperatorSurfaceRoot})
	tmpl, err = tmpl.ParseFS(cfg.TemplatesFS, "discourse_operator.html")
	if err != nil {
		return nil, err
	}

	return &DiscourseOperatorHandler{
		db:              cfg.DB,
		logger:          cfg.Logger,
		authConfig:      cfg.AuthConfig,
		apiClient:       cfg.Client,
		temporal:        cfg.Temporal,
		configured:      cfg.Configured,
		description:     cfg.Description,
		sweepScheduleID: cfg.SweepScheduleID,
		templates:       server.NewSafeTemplates(tmpl, cfg.Logger),
	}, nil
}

// buildPageData assembles the body payload. API/Temporal-dependent sections
// are only populated when configured (spec: the unconfigured page shows no
// error-state sync data).
func (h *DiscourseOperatorHandler) buildPageData(r *http.Request) OperatorPageData {
	data := OperatorPageData{Configured: h.configured, Description: h.description}
	if !h.configured {
		return data
	}
	ctx := r.Context()
	q := dcmod.New(h.db)

	// Fetched before the mappings loop so the same catalog backs both the
	// picker's friendly names and each mapping row's leading display name
	// (ui-vocabulary 4.3) — one lookup, two consumers.
	keys, err := q.ListOwnedResourceKeys(ctx)
	if err != nil {
		h.logger.Error("discourse operator: resource keys query failed", slog.Any("error", err))
	}
	displayNames := make(map[string]string, len(keys))
	for _, k := range keys {
		displayNames[k.ResourceKey] = k.DisplayName
		data.ResourceKeys = append(data.ResourceKeys, ResourceKeyOption{Key: k.ResourceKey, DisplayName: k.DisplayName})
	}

	mappings, err := q.ListGroupMappings(ctx)
	if err != nil {
		h.logger.Error("discourse operator: list mappings failed", slog.Any("error", err))
		data.Error = "Failed to load group mappings. Details are in the server logs."
		return data
	}
	seenKeys := map[string]bool{}
	seenPersons := map[string]bool{}
	for _, m := range mappings {
		data.Mappings = append(data.Mappings, MappingViewModel{
			MappingID:   m.MappingID,
			ResourceKey: m.ResourceKey,
			DisplayName: displayNames[m.ResourceKey],
			GroupName:   m.GroupName,
			GroupID:     m.DiscourseGroupID,
			CreatedAt:   m.CreatedAt.Format("Jan 2, 2006"),
			DeleteURL:   "/partials/operator/discourse/mappings/" + m.MappingID,
		})
		if seenKeys[m.ResourceKey] {
			continue
		}
		seenKeys[m.ResourceKey] = true
		unlinked, uErr := q.ListEntitledUnlinkedPersons(ctx, m.ResourceKey)
		if uErr != nil {
			h.logger.Error("discourse operator: unlinked query failed", slog.Any("error", uErr))
			continue
		}
		for _, p := range unlinked {
			if seenPersons[p.PersonID] {
				continue
			}
			seenPersons[p.PersonID] = true
			data.Unlinked = append(data.Unlinked, UnlinkedPersonViewModel{
				DisplayName: p.DisplayName, Email: p.PrimaryEmail,
			})
		}
	}

	conflicts, err := q.ListConflictedUserLinks(ctx)
	if err != nil {
		h.logger.Error("discourse operator: conflicts query failed", slog.Any("error", err))
	}
	for _, c := range conflicts {
		data.Conflicts = append(data.Conflicts, ConflictViewModel{
			DiscourseUsername: c.DiscourseUsername, PersonID: c.PersonID,
		})
	}

	data.SweepStatus, data.SweepTime = h.sweepHealth(r)
	data.Form = forms.Render(mappingForm, forms.Binding{
		Mode:    forms.ModeUnbound,
		Options: mappingFormOptions(data.ResourceKeys),
	})
	return data
}

// sweepHealth reports the most recent schedule-spawned sweep's status and
// time; "no sweep yet" when the schedule hasn't fired or Temporal is absent.
func (h *DiscourseOperatorHandler) sweepHealth(r *http.Request) (string, string) {
	status, when := workflows.ScheduleRunStatus(r.Context(), h.temporal, h.sweepScheduleID)
	if status == "" {
		return "No sweep has run yet", ""
	}
	return status, when
}

// GetPage handles GET <OperatorSurfacePath>.
func (h *DiscourseOperatorHandler) GetPage(w http.ResponseWriter, r *http.Request) {
	page := server.BuildOperatorPageData(r, h.authConfig, h.db, h.logger)
	// Second-level page of the Integrations section: the section's sidebar
	// entry lights up via ActiveCapability (the page is reached from the
	// Integrations home, not the sidebar); ia-position nests under the landing.
	page.IAPosition = "integration:integrations:discourse"
	page.ActiveCapability = "integrations"
	page.BodyTemplate = "discourse_operator.html"
	page.BodyData = h.buildPageData(r)
	h.templates.Render(w, "operator.html", page)
}

// renderBody renders the body partial alone (HTMX swap responses).
func (h *DiscourseOperatorHandler) renderBody(w http.ResponseWriter, status int, data OperatorPageData) {
	w.WriteHeader(status)
	h.templates.Render(w, "discourse_operator.html", data)
}

// CreateMapping handles POST /partials/operator/discourse/mappings: validate
// against the forum (group exists, not automatic), then insert (spec:
// "Entitlement-to-group mapping management"). It reads the body through the
// mapping declaration and never through r.FormValue (form-library "The
// handler parses through the declaration"): a resource key outside the
// options the select offered is refused by Parse itself, never resolved to
// a default (finding FA-8).
func (h *DiscourseOperatorHandler) CreateMapping(w http.ResponseWriter, r *http.Request) {
	keys, err := dcmod.New(h.db).ListOwnedResourceKeys(r.Context())
	if err != nil {
		h.logger.Error("discourse operator: resource keys query failed", slog.Any("error", err))
	}
	var resourceKeys []ResourceKeyOption
	for _, k := range keys {
		resourceKeys = append(resourceKeys, ResourceKeyOption{Key: k.ResourceKey, DisplayName: k.DisplayName})
	}
	options := mappingFormOptions(resourceKeys)
	values, errs := mappingForm.ParseWith(r, options)

	fail := func() {
		data := h.buildPageData(r)
		data.Form = forms.Render(mappingForm, forms.Binding{
			Mode:    forms.ModeSubmission,
			Values:  values,
			Errors:  errs,
			Options: options,
		})
		h.renderBody(w, http.StatusUnprocessableEntity, data)
	}

	if errs.Any() {
		fail()
		return
	}
	resourceKey := values.String("resource_key")
	groupName := values.String("group_name")

	group, err := h.apiClient.GetGroup(r.Context(), groupName)
	if err != nil {
		h.logger.Error("discourse operator: group validation failed", slog.Any("error", err))
		errs.Field("group_name", "Could not reach the forum to validate the group. Try again.")
		fail()
		return
	}
	if group == nil {
		errs.Field("group_name", "No group with that name exists on the forum.")
		fail()
		return
	}
	if group.Automatic {
		errs.Field("group_name", "That is an automatic Discourse group; its membership cannot be managed externally. Choose a manually-created group.")
		fail()
		return
	}

	if _, err := dcmod.New(h.db).CreateGroupMapping(r.Context(), dcmod.CreateGroupMappingParams{
		ResourceKey: resourceKey, GroupName: group.Name, DiscourseGroupID: group.ID,
	}); err != nil {
		if fe, ok := web.FieldErrorsFromDB(err, groupMappingConstraints); ok {
			for field, msg := range fe {
				errs.Field(field, msg)
			}
			fail()
			return
		}
		h.logger.Error("discourse operator: create mapping failed", slog.Any("error", err))
		http.Error(w, "Internal error", http.StatusInternalServerError)
		return
	}

	h.fireToast(w, "Group mapping created")
	h.renderBody(w, http.StatusOK, h.buildPageData(r))
}

// DeleteMapping handles DELETE /partials/operator/discourse/mappings/{mappingID}.
// Unmapping stops management; forum-side membership is left as-is (spec:
// "Unmapping a group").
func (h *DiscourseOperatorHandler) DeleteMapping(w http.ResponseWriter, r *http.Request) {
	rows, err := dcmod.New(h.db).DeleteGroupMapping(r.Context(), r.PathValue("mappingID"))
	if err != nil {
		h.logger.Error("discourse operator: delete mapping failed", slog.Any("error", err))
		http.Error(w, "Internal error", http.StatusInternalServerError)
		return
	}
	if rows == 0 {
		http.Error(w, "Not found", http.StatusNotFound)
		return
	}
	h.fireToast(w, "Group mapping deleted")
	h.renderBody(w, http.StatusOK, h.buildPageData(r))
}

func (h *DiscourseOperatorHandler) fireToast(w http.ResponseWriter, message string) {
	if payload, err := json.Marshal(map[string]string{"showSuccessToast": message}); err == nil {
		w.Header().Set("HX-Trigger", string(payload))
	}
}

// ---- Page-anatomy pipeline (anatomy sweep group 9). Same shape as the
// FedWiki operator page: the shared parts come from web.ParseUIPartials,
// the data uses the server package's part types so badge labels and
// tones stay in the one badge map (design D3).

func (d OperatorPageData) Header() server.PageHeader {
	lead := "Delivery of forum access to entitled members: group mappings, member-to-forum account links, and sync health."
	if d.Description != "" {
		lead = d.Description
	}
	return server.PageHeader{
		Title:  "Discourse forum",
		Lead:   lead,
		Crumbs: []server.Link{{Label: "Integrations", URL: "/operator/integrations"}},
		Action: &server.Link{Label: "Settings", URL: "/operator/integrations/discourse/settings"},
	}
}

// NotConfigured is the page's blocked state: the integration is
// registered but dormant until its keys are set, and the settings page
// is where an operator sees which keys those are.
func (OperatorPageData) NotConfigured() server.EmptyStateParams {
	return server.EmptyStateParams{
		Blocked:           true,
		BlockerCopy:       "Discourse is not configured. Set discourse-base-url and discourse-api-key (and optionally discourse-webhook-secret) to enable the integration; until then it is registered but dormant.",
		PrerequisiteURL:   "/operator/integrations/discourse/settings",
		PrerequisiteLabel: "Open Discourse settings",
	}
}

func (OperatorPageData) SweepHeader() server.SectionHeader {
	return server.SectionHeader{Title: "Sync health", Help: "The sweep is the periodic background job that reconciles forum group membership with entitlements."}
}

func (OperatorPageData) MapGroupHeader() server.SectionHeader {
	return server.SectionHeader{Title: "Map a group"}
}

func (d OperatorPageData) MappingsHeader() server.SectionHeader {
	h := server.SectionHeader{Title: "Group mappings"}
	switch n := len(d.Mappings); {
	case n == 1:
		h.Count = "1 mapping"
	case n > 1:
		h.Count = fmt.Sprintf("%d mappings", n)
	}
	return h
}

func (OperatorPageData) NoMappings() server.EmptyStateParams {
	return server.EmptyStateParams{
		Headline: "No groups are mapped yet.",
		Note:     "Map an entitlement to a Discourse group above to start delivering forum access.",
	}
}

func (d OperatorPageData) UnlinkedHeader() server.SectionHeader {
	h := server.SectionHeader{Title: "Entitled but unlinked"}
	switch n := len(d.Unlinked); {
	case n == 1:
		h.Count = "1 person"
	case n > 1:
		h.Count = fmt.Sprintf("%d people", n)
	}
	return h
}

func (d OperatorPageData) ConflictsHeader() server.SectionHeader {
	h := server.SectionHeader{Title: "Link conflicts"}
	switch n := len(d.Conflicts); {
	case n == 1:
		h.Count = "1 conflict"
	case n > 1:
		h.Count = fmt.Sprintf("%d conflicts", n)
	}
	return h
}