package api

import (
	"encoding/json"
	"net/http"
	"strconv"

	"github.com/gorilla/mux"
)

// HashIDsResponse is the response for GET /api/metadata/hash-ids
type HashIDsResponse struct {
	HashIds []string `json:"hashIds"`
	Count   int      `json:"count"`
}

// MetadataListItem represents a file in the metadata list
type MetadataListItem struct {
	HashID   string `json:"hashId"`
	Title    string `json:"title,omitempty"`
	FileName string `json:"fileName,omitempty"`
	FilePath string `json:"filePath,omitempty"`
	Type     string `json:"type,omitempty"`
	Year     string `json:"year,omitempty"`
}

// MetadataListResponse is the response for GET /api/metadata/list
type MetadataListResponse struct {
	Items []MetadataListItem `json:"items"`
	Count int                `json:"count"`
	Total int                `json:"total"`
}

// MetadataSearchRequest is the request body for POST /api/metadata/search
type MetadataSearchRequest struct {
	Query         string `json:"query,omitempty"`
	HashID        string `json:"hashId,omitempty"`
	Property      string `json:"property,omitempty"`
	PropertyValue string `json:"propertyValue,omitempty"`
	Limit         int    `json:"limit,omitempty"`

	// Filters is the structured form: AND across entries, OR within an
	// entry's Values. Narrowed in SQL through the field index alongside the
	// free-text Query, then verified per record (see serveIndexedSearch), so an
	// id-anchored lookup costs an index probe rather than a read per record.
	//
	// Property/PropertyValue is the single-filter legacy shape and folds into
	// this list (see normalizedFilters) with Exact=false, preserving its
	// substring semantics byte-for-byte.
	Filters []MetadataFilter `json:"filters,omitempty"`
}

// MetadataFilter is one structured constraint on a record.
//
// A record satisfies it when ANY of Values matches, and a search result must
// satisfy EVERY filter (OR within, AND across). An entry with no usable value
// constrains nothing — same rule the gateway's `genres_filter_matches` uses, so
// a caller that lowers an empty filter doesn't accidentally empty the result.
type MetadataFilter struct {
	// Property is the field name, WITHOUT a key-set suffix: `genres`, not
	// `genres/Action`. Both storage shapes are probed — see recordMatchesFilter.
	Property string `json:"property"`
	// Values are OR'd. Compared case-insensitively.
	Values []string `json:"values,omitempty"`
	// Exact selects CSV-exact comparison (the semantics meta-gateway's
	// `any_csv_value_matches` applies at its own Layer-B re-filter) over
	// substring containment. Callers doing identity lookups want this: with a
	// result limit, a substring match on `tmdbid=1405` also admits `21405` and
	// can crowd the real matches out of the page.
	Exact bool `json:"exact,omitempty"`
}

// MetadataSearchResult is a single search result
type MetadataSearchResult struct {
	HashID   string            `json:"hashId"`
	Metadata map[string]string `json:"metadata"`
}

// MetadataSearchResponse is the response for POST /api/metadata/search
type MetadataSearchResponse struct {
	Results []MetadataSearchResult `json:"results"`
	Count   int                    `json:"count"`
	Total   int                    `json:"total"`
}

// MetadataBatchUpdateRequest is the request body for POST /api/metadata/batch
type MetadataBatchUpdateRequest struct {
	Updates []MetadataBatchItem `json:"updates"`
}

// MetadataBatchItem is a single item in a batch update
type MetadataBatchItem struct {
	HashID     string            `json:"hashId"`
	Metadata   map[string]string `json:"metadata,omitempty"`
	Properties map[string]string `json:"properties,omitempty"`
}

// MetadataBatchResult is a single result from a batch update
type MetadataBatchResult struct {
	HashID string `json:"hashId"`
	Status string `json:"status"`
	Error  string `json:"error,omitempty"`
}

// MetadataBatchResponse is the response for POST /api/metadata/batch
type MetadataBatchResponse struct {
	Status  string                `json:"status"`
	Total   int                   `json:"total"`
	Success int                   `json:"success"`
	Errors  int                   `json:"errors"`
	Results []MetadataBatchResult `json:"results"`
}

// PropertyUpdateRequest is the request body for PUT /api/metadata/{hashId}/property
type PropertyUpdateRequest struct {
	Property string `json:"property"`
	Value    string `json:"value"`
}

// handleGetHashIds handles GET /api/metadata/hash-ids
func (s *Server) handleGetHashIds(w http.ResponseWriter, r *http.Request) {
	if !s.storage.IsConnected() {
		writeError(w, http.StatusServiceUnavailable, "storage not connected")
		return
	}

	hashIDs, err := s.storage.GetAllHashIDs()
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}

	response := HashIDsResponse{
		HashIds: hashIDs,
		Count:   len(hashIDs),
	}

	writeJSON(w, http.StatusOK, response)
}

// handleListMetadata handles GET /api/metadata/list
func (s *Server) handleListMetadata(w http.ResponseWriter, r *http.Request) {
	if !s.storage.IsConnected() {
		writeError(w, http.StatusServiceUnavailable, "storage not connected")
		return
	}

	// Parse pagination parameters
	offsetStr := r.URL.Query().Get("offset")
	limitStr := r.URL.Query().Get("limit")

	offset := 0
	if offsetStr != "" {
		if o, err := strconv.Atoi(offsetStr); err == nil {
			offset = o
		}
	}

	limit := 100
	if limitStr != "" {
		if l, err := strconv.Atoi(limitStr); err == nil && l > 0 {
			limit = l
		}
	}

	// Get all hash IDs
	allHashIDs, err := s.storage.GetAllHashIDs()
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}

	total := len(allHashIDs)

	// Apply pagination
	end := offset + limit
	if end > total {
		end = total
	}

	var items []MetadataListItem
	if offset < total {
		for _, hashID := range allHashIDs[offset:end] {
			metadata, err := s.storage.GetMetadataFlat(hashID)
			if err != nil || metadata == nil {
				continue
			}

			item := MetadataListItem{
				HashID:   hashID,
				Title:    metadata["title"],
				FileName: metadata["fileName"],
				FilePath: metadata["filePath"],
				Type:     metadata["type"],
				Year:     metadata["year"],
			}
			items = append(items, item)
		}
	}

	response := MetadataListResponse{
		Items: items,
		Count: len(items),
		Total: total,
	}

	writeJSON(w, http.StatusOK, response)
}

// handleGetMetadataByHashId handles GET /api/metadata/{hashId}
func (s *Server) handleGetMetadataByHashId(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	hashID := vars["hashId"]

	if hashID == "" {
		writeError(w, http.StatusBadRequest, "hash ID is required")
		return
	}

	if !s.storage.IsConnected() {
		writeError(w, http.StatusServiceUnavailable, "storage not connected")
		return
	}

	// Same resolution as the PUT below: callers hold a CID, not the root.
	hashID = s.storage.ResolveRoot(hashID)

	metadata, err := s.storage.GetMetadataFlat(hashID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}

	if metadata == nil {
		writeError(w, http.StatusNotFound, "metadata not found")
		return
	}

	response := MetadataResponse{
		HashID:   hashID,
		Metadata: metadata,
	}

	writeJSON(w, http.StatusOK, response)
}

// handleUpdateMetadataByHashId handles PUT /api/metadata/{hashId}
func (s *Server) handleUpdateMetadataByHashId(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	hashID := vars["hashId"]

	if hashID == "" {
		writeError(w, http.StatusBadRequest, "hash ID is required")
		return
	}

	if !s.storage.IsConnected() {
		writeError(w, http.StatusServiceUnavailable, "storage not connected")
		return
	}

	// The {hashId} in the URL is whatever CID the caller knows the file by —
	// the gateway's auto-store keys this PUT by the hash it just computed
	// (dispatch.rs → store_metadata_only), which for a usenet→IPFS fetch is
	// the dag-pb root, not the nzb-release cid the record was minted under.
	// Without resolving, the write lands on file:<thatCid>/* and forks a
	// second root for a file that already has one: a full duplicate record,
	// cross-linked and separately indexed, which every downstream ingest then
	// sees as two files. Unknown CIDs pass through unchanged, so a genuinely
	// new gateway record still mints its root at the hash.
	hashID = s.storage.ResolveRoot(hashID)

	var metadata map[string]string
	if err := json.NewDecoder(r.Body).Decode(&metadata); err != nil {
		writeError(w, http.StatusBadRequest, "invalid JSON body")
		return
	}

	// Exclude internal processing status field
	delete(metadata, "processingStatus")

	if err := s.storage.SetMetadataFlat(hashID, metadata); err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}

	writeJSON(w, http.StatusOK, map[string]interface{}{
		"status":  "ok",
		"hashId":  hashID,
		"message": "Metadata updated successfully",
	})
}

// handleDeleteMetadataByHashId handles DELETE /api/metadata/{hashId}
func (s *Server) handleDeleteMetadataByHashId(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	hashID := vars["hashId"]

	if hashID == "" {
		writeError(w, http.StatusBadRequest, "hash ID is required")
		return
	}

	if !s.storage.IsConnected() {
		writeError(w, http.StatusServiceUnavailable, "storage not connected")
		return
	}

	// meta-gateway retracts a dropped hit by whichever CID it holds
	// (meta_core.rs `delete`, which documents this resolution as a
	// precondition). Without it, deleting by a non-root CID is a silent
	// no-op and the retracted record lingers.
	hashID = s.storage.ResolveRoot(hashID)

	deletedCount, err := s.storage.DeleteMetadata(hashID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}

	writeJSON(w, http.StatusOK, map[string]interface{}{
		"status":      "ok",
		"hashId":      hashID,
		"deletedKeys": deletedCount,
	})
}

// handleMetadataGetProperty handles GET /api/metadata/{hashId}/property?property=X
func (s *Server) handleMetadataGetProperty(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	hashID := vars["hashId"]
	property := r.URL.Query().Get("property")

	if hashID == "" {
		writeError(w, http.StatusBadRequest, "hash ID is required")
		return
	}

	if property == "" {
		writeError(w, http.StatusBadRequest, "property parameter is required")
		return
	}

	if !s.storage.IsConnected() {
		writeError(w, http.StatusServiceUnavailable, "storage not connected")
		return
	}

	value, err := s.storage.GetProperty(hashID, property)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}

	if value == "" {
		writeError(w, http.StatusNotFound, "property not found")
		return
	}

	writeJSON(w, http.StatusOK, map[string]interface{}{
		"hashId":   hashID,
		"property": property,
		"value":    value,
	})
}

// handleMetadataUpdateProperty handles PUT /api/metadata/{hashId}/property
func (s *Server) handleMetadataUpdateProperty(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	hashID := vars["hashId"]

	if hashID == "" {
		writeError(w, http.StatusBadRequest, "hash ID is required")
		return
	}

	if !s.storage.IsConnected() {
		writeError(w, http.StatusServiceUnavailable, "storage not connected")
		return
	}

	var req PropertyUpdateRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid JSON body")
		return
	}

	if req.Property == "" {
		writeError(w, http.StatusBadRequest, "property is required")
		return
	}

	if err := s.storage.SetProperty(hashID, req.Property, req.Value); err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}

	writeJSON(w, http.StatusOK, map[string]interface{}{
		"status":   "ok",
		"hashId":   hashID,
		"property": req.Property,
		"value":    req.Value,
		"message":  "Property updated successfully",
	})
}

// handleSearchMetadata handles POST /api/metadata/search
func (s *Server) handleSearchMetadata(w http.ResponseWriter, r *http.Request) {
	if !s.storage.IsConnected() {
		writeError(w, http.StatusServiceUnavailable, "storage not connected")
		return
	}

	var req MetadataSearchRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid JSON body")
		return
	}

	if req.Limit == 0 {
		req.Limit = 100
	}

	// If hashId is provided, do exact match
	if req.HashID != "" {
		metadata, err := s.storage.GetMetadataFlat(req.HashID)
		if err != nil {
			writeError(w, http.StatusInternalServerError, err.Error())
			return
		}
		if metadata != nil {
			writeJSON(w, http.StatusOK, MetadataSearchResponse{
				Results: []MetadataSearchResult{{HashID: req.HashID, Metadata: metadata}},
				Count:   1,
				Total:   1,
			})
			return
		}
		writeJSON(w, http.StatusOK, MetadataSearchResponse{
			Results: []MetadataSearchResult{},
			Count:   0,
			Total:   0,
		})
		return
	}

	// Everything else — free text, structured filters, both, or neither
	// (which returns the first `limit`) — is served from the store's derived
	// search indexes (search_index.go → storage.Search).
	//
	// There is deliberately no second path. The property branch used to fall
	// through to a `GetAllHashIDs` + per-record `GetMetadataFlat` scan, which
	// is what made an id-anchored lookup 3.63s over ~20k records (vs 10ms for
	// the free-text branch on the same corpus) and kept meta-core out of the
	// gateway's anchored search path entirely. The index already holds every
	// field of every record, so that scan was re-reading data it had in hand.
	s.serveIndexedSearch(w, req)
}

// handleBatchUpdate handles POST /api/metadata/batch
func (s *Server) handleBatchUpdate(w http.ResponseWriter, r *http.Request) {
	if !s.storage.IsConnected() {
		writeError(w, http.StatusServiceUnavailable, "storage not connected")
		return
	}

	var req MetadataBatchUpdateRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid JSON body")
		return
	}

	if len(req.Updates) == 0 {
		writeError(w, http.StatusBadRequest, "updates array is required")
		return
	}

	var results []MetadataBatchResult
	successCount := 0
	errorCount := 0

	for _, update := range req.Updates {
		if update.HashID == "" {
			results = append(results, MetadataBatchResult{
				HashID: "unknown",
				Status: "error",
				Error:  "Missing hash ID",
			})
			errorCount++
			continue
		}

		var updateErr error

		// Update complete metadata
		if update.Metadata != nil {
			// Exclude internal processing status
			delete(update.Metadata, "processingStatus")
			updateErr = s.storage.SetMetadataFlat(update.HashID, update.Metadata)
		}

		// Update individual properties
		if updateErr == nil && update.Properties != nil {
			for property, value := range update.Properties {
				if err := s.storage.SetProperty(update.HashID, property, value); err != nil {
					updateErr = err
					break
				}
			}
		}

		if updateErr != nil {
			results = append(results, MetadataBatchResult{
				HashID: update.HashID,
				Status: "error",
				Error:  updateErr.Error(),
			})
			errorCount++
		} else {
			results = append(results, MetadataBatchResult{
				HashID: update.HashID,
				Status: "ok",
			})
			successCount++
		}
	}

	writeJSON(w, http.StatusOK, MetadataBatchResponse{
		Status:  "completed",
		Total:   len(results),
		Success: successCount,
		Errors:  errorCount,
		Results: results,
	})
}

// handleClearMetadata handles POST /api/metadata/clear
func (s *Server) handleClearMetadata(w http.ResponseWriter, r *http.Request) {
	if !s.storage.IsConnected() {
		writeError(w, http.StatusServiceUnavailable, "storage not connected")
		return
	}

	deletedCount, err := s.storage.ClearAllMetadata()
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}

	writeJSON(w, http.StatusOK, map[string]interface{}{
		"status":       "ok",
		"message":      "Metadata cleared",
		"deletedCount": deletedCount,
	})
}