package handlers

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"log/slog"
	"net/http"
	"sync"
	"time"

	"atcr.io/pkg/appview/db"
	"atcr.io/pkg/appview/middleware"
	"atcr.io/pkg/atproto"
	"atcr.io/pkg/auth"
)

// DeleteAccountRequest represents the GDPR account deletion request
type DeleteAccountRequest struct {
	DeletePDSRecords bool   `json:"delete_pds_records"`
	Confirmation     string `json:"confirmation"` // Must be "DELETE <handle>" to confirm
}

// DeleteAccountResponse represents the result of account deletion
type DeleteAccountResponse struct {
	Success        bool               `json:"success"`
	AppViewDeleted bool               `json:"appview_deleted"`
	PDSDeleted     bool               `json:"pds_deleted,omitempty"`
	PDSCollections map[string]int     `json:"pds_collections_deleted,omitempty"`
	HoldResults    []HoldDeleteResult `json:"hold_results"`
	Errors         []string           `json:"errors,omitempty"`
}

// HoldDeleteResult represents the result of deleting data from a single hold
type HoldDeleteResult struct {
	HoldDID       string `json:"hold_did"`
	Relationship  string `json:"relationship"` // "captain" or "crew_member"
	Status        string `json:"status"`       // "success", "failed", "offline"
	Error         string `json:"error,omitempty"`
	CrewDeleted   bool   `json:"crew_deleted,omitempty"`
	LayersDeleted int    `json:"layers_deleted,omitempty"`
	StatsDeleted  int    `json:"stats_deleted,omitempty"`
	PostsDeleted  int    `json:"posts_deleted,omitempty"`
}

// DeleteAccountHandler handles GDPR account deletion requests
type DeleteAccountHandler struct {
	BaseUIHandler
}

func (h *DeleteAccountHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	// Get authenticated user from middleware
	user := middleware.GetUser(r)
	if user == nil {
		http.Error(w, "Unauthorized", http.StatusUnauthorized)
		return
	}

	// Parse request body
	var req DeleteAccountRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, "Invalid request body", http.StatusBadRequest)
		return
	}

	// Require confirmation with handle (e.g., "DELETE alice.bsky.social")
	expectedConfirmation := "DELETE " + user.Handle
	if req.Confirmation != expectedConfirmation {
		http.Error(w, fmt.Sprintf("Confirmation required: must send confirmation='DELETE %s'", user.Handle), http.StatusBadRequest)
		return
	}

	slog.Info("Processing account deletion request",
		"component", "delete",
		"did", user.DID,
		"delete_pds_records", req.DeletePDSRecords)

	response := DeleteAccountResponse{
		HoldResults: []HoldDeleteResult{},
	}

	// 1. Delete from each hold where user is a member
	holdResults := h.deleteFromHolds(r.Context(), user)
	response.HoldResults = holdResults

	// 2. If requested, delete PDS records
	if req.DeletePDSRecords {
		pdsResults, err := h.deletePDSRecords(r.Context(), user)
		if err != nil {
			slog.Error("Failed to delete PDS records",
				"component", "delete",
				"did", user.DID,
				"error", err)
			response.Errors = append(response.Errors, fmt.Sprintf("PDS deletion error: %v", err))
		} else {
			response.PDSDeleted = true
			response.PDSCollections = pdsResults
		}
	}

	// 3. Delete from AppView database (last, since we need OAuth tokens for above steps)
	if err := db.DeleteUserDataFull(h.DB, h.OAuthStore, user.DID); err != nil {
		slog.Error("Failed to delete AppView data",
			"component", "delete",
			"did", user.DID,
			"error", err)
		response.Errors = append(response.Errors, fmt.Sprintf("AppView deletion error: %v", err))
	} else {
		response.AppViewDeleted = true
	}

	// Set success if AppView data was deleted (main requirement)
	response.Success = response.AppViewDeleted

	slog.Info("Account deletion completed",
		"component", "delete",
		"did", user.DID,
		"success", response.Success,
		"holds_processed", len(response.HoldResults),
		"pds_deleted", response.PDSDeleted)

	w.Header().Set("Content-Type", "application/json")
	if err := json.NewEncoder(w).Encode(response); err != nil {
		slog.Error("Failed to encode response", "error", err)
	}
}

// deleteFromHolds deletes user data from all holds where they are a member
func (h *DeleteAccountHandler) deleteFromHolds(ctx context.Context, user *db.User) []HoldDeleteResult {
	var results []HoldDeleteResult

	// Build metadata map: holdDID → relationship
	holdMeta := make(map[string]string)

	// Get holds where user is captain
	if h.DB != nil {
		captainHolds, err := db.GetCaptainRecordsForOwner(h.DB, user.DID)
		if err != nil {
			slog.Warn("Failed to get captain records for deletion",
				"component", "delete",
				"did", user.DID,
				"error", err)
		} else {
			for _, hold := range captainHolds {
				holdMeta[hold.HoldDID] = "captain"
			}
		}
	}

	// Get crew memberships from database
	memberships, err := db.GetCrewMemberships(h.DB, user.DID)
	if err != nil {
		slog.Warn("Failed to get crew memberships for deletion",
			"component", "delete",
			"did", user.DID,
			"error", err)
	} else {
		for _, m := range memberships {
			// Don't overwrite captain relationship
			if _, exists := holdMeta[m.HoldDID]; !exists {
				holdMeta[m.HoldDID] = "crew_member"
			}
		}
	}

	if len(holdMeta) == 0 {
		return results
	}

	// Delete from each hold concurrently with timeout
	var wg sync.WaitGroup
	resultChan := make(chan HoldDeleteResult, len(holdMeta))

	for holdDID, relationship := range holdMeta {
		wg.Add(1)
		go func(holdDID, relationship string) {
			defer wg.Done()
			result := h.deleteFromSingleHold(ctx, user, holdDID, relationship)
			resultChan <- result
		}(holdDID, relationship)
	}

	// Wait for all goroutines to complete
	wg.Wait()
	close(resultChan)

	// Collect results
	for result := range resultChan {
		results = append(results, result)
	}

	return results
}

// deleteFromSingleHold deletes user data from a single hold
func (h *DeleteAccountHandler) deleteFromSingleHold(ctx context.Context, user *db.User, holdDID, relationship string) HoldDeleteResult {
	// Resolve hold DID to URL
	holdURL := atproto.ResolveHoldURL(holdDID)
	endpoint := holdURL + "/xrpc/io.atcr.hold.deleteUserData"

	result := HoldDeleteResult{
		HoldDID:      holdDID,
		Relationship: relationship,
		Status:       "failed",
	}

	// Check if we have OAuth refresher (needed for service tokens)
	if h.Refresher == nil {
		result.Error = "OAuth not configured - cannot authenticate to hold"
		return result
	}

	// Create context with timeout (10 seconds per hold for deletion)
	timeoutCtx, cancel := context.WithTimeout(ctx, 10*time.Second)
	defer cancel()

	// Get service token from user's PDS
	serviceToken, err := auth.GetOrFetchServiceToken(timeoutCtx, h.Refresher, user.DID, holdDID, user.PDSEndpoint)
	if err != nil {
		slog.Warn("Failed to get service token for hold deletion",
			"component", "delete",
			"hold_did", holdDID,
			"user_did", user.DID,
			"error", err)
		result.Error = fmt.Sprintf("Failed to authenticate: %v", err)
		return result
	}

	// Create request
	req, err := http.NewRequestWithContext(timeoutCtx, "DELETE", endpoint, nil)
	if err != nil {
		result.Error = fmt.Sprintf("Failed to create request: %v", err)
		return result
	}

	// Set auth header
	req.Header.Set("Authorization", "Bearer "+serviceToken)

	// Make request
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		slog.Warn("Hold deletion request failed",
			"component", "delete",
			"hold_did", holdDID,
			"endpoint", endpoint,
			"error", err)
		result.Status = "offline"
		result.Error = fmt.Sprintf("Could not contact hold: %v", err)
		return result
	}
	defer resp.Body.Close()

	// Check response status
	if resp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(resp.Body)
		result.Error = fmt.Sprintf("Hold returned status %d: %s", resp.StatusCode, string(body))
		return result
	}

	// Parse response
	var holdResponse struct {
		Success       bool `json:"success"`
		CrewDeleted   bool `json:"crew_deleted"`
		LayersDeleted int  `json:"layers_deleted"`
		StatsDeleted  int  `json:"stats_deleted"`
		PostsDeleted  int  `json:"posts_deleted"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&holdResponse); err != nil {
		result.Error = fmt.Sprintf("Failed to parse response: %v", err)
		return result
	}

	// Update result with success data
	result.Status = "success"
	result.CrewDeleted = holdResponse.CrewDeleted
	result.LayersDeleted = holdResponse.LayersDeleted
	result.StatsDeleted = holdResponse.StatsDeleted
	result.PostsDeleted = holdResponse.PostsDeleted

	slog.Debug("Successfully deleted data from hold",
		"component", "delete",
		"hold_did", holdDID,
		"user_did", user.DID,
		"crew_deleted", holdResponse.CrewDeleted,
		"layers_deleted", holdResponse.LayersDeleted,
		"stats_deleted", holdResponse.StatsDeleted,
		"posts_deleted", holdResponse.PostsDeleted)

	return result
}

// deletePDSRecords deletes all io.atcr.* records from the user's PDS
func (h *DeleteAccountHandler) deletePDSRecords(ctx context.Context, user *db.User) (map[string]int, error) {
	if h.Refresher == nil {
		return nil, fmt.Errorf("OAuth not configured")
	}

	results := make(map[string]int)

	// Create ATProto client with session provider
	client := atproto.NewClientWithSessionProvider(user.PDSEndpoint, user.DID, h.Refresher)

	// Collections to delete
	collections := []string{
		atproto.ManifestCollection, // io.atcr.manifest
		atproto.TagCollection,      // io.atcr.tag
		atproto.StarCollection,     // io.atcr.sailor.star
		atproto.RepoPageCollection, // io.atcr.repo.page
	}

	for _, collection := range collections {
		deleted, err := client.DeleteAllRecordsInCollection(ctx, collection)
		if err != nil {
			slog.Warn("Failed to delete records in collection",
				"component", "delete",
				"did", user.DID,
				"collection", collection,
				"error", err)
			// Continue with other collections
		}
		results[collection] = deleted
		if deleted > 0 {
			slog.Debug("Deleted records from collection",
				"component", "delete",
				"did", user.DID,
				"collection", collection,
				"count", deleted)
		}
	}

	// Delete sailor profile (single record at rkey "self")
	err := client.DeleteRecord(ctx, atproto.SailorProfileCollection, "self")
	if err != nil {
		slog.Warn("Failed to delete sailor profile",
			"component", "delete",
			"did", user.DID,
			"error", err)
	} else {
		results[atproto.SailorProfileCollection] = 1
	}

	return results, nil
}