package handlers

import (
	"fmt"
	"net/http"
	"strconv"

	apperrors "veza-backend-api/internal/errors"
	"veza-backend-api/internal/services"
	"veza-backend-api/internal/tracing"

	"github.com/gin-gonic/gin"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/codes"
	"go.opentelemetry.io/otel/trace"
)

var SearchHandlersInstance *SearchHandlers

// SearchServiceInterface defines the interface for search operations
// This allows for easier testing with mocks
type SearchServiceInterface interface {
	Search(query string, types []string, filters *services.SearchFilters) (*services.SearchResult, error)
	Suggestions(query string, limit int) (*services.SearchResult, error)
}

type SearchHandlers struct {
	searchService SearchServiceInterface
}

func NewSearchHandlers(searchService *services.SearchService) {
	SearchHandlersInstance = &SearchHandlers{
		searchService: searchService,
	}
}

// NewSearchHandlersWithInterface creates new search handlers with an interface (for testing)
func NewSearchHandlersWithInterface(searchService SearchServiceInterface) *SearchHandlers {
	SearchHandlersInstance = &SearchHandlers{
		searchService: searchService,
	}
	return SearchHandlersInstance
}

// Search performs a full-text search across tracks, users, and playlists
// @Summary      Unified search
// @Description  Postgres FTS-backed search across tracks, users, and playlists. Optional `type` filter accepts repeated values (e.g., ?type=track&type=user). v1.0.9 W4 Day 18 adds faceted filters on tracks: genre, musical_key, bpm_min, bpm_max, year_from, year_to (all optional ; ignored on user/playlist results).
// @Tags         Search
// @Produce      json
// @Param        q           query  string   true  "Search query"
// @Param        type        query  []string false "Restrict to one or more entity types: track, user, playlist" collectionFormat(multi)
// @Param        genre       query  string   false "Filter tracks by genre (exact match)"
// @Param        musical_key query  string   false "Filter tracks by musical key (e.g. C, Am)"
// @Param        bpm_min     query  int      false "Minimum BPM (1..999)"
// @Param        bpm_max     query  int      false "Maximum BPM (1..999)"
// @Param        year_from   query  int      false "Minimum release year (1900..2100)"
// @Param        year_to     query  int      false "Maximum release year (1900..2100)"
// @Param        cursor      query  string   false "Opaque pagination cursor"
// @Param        limit       query  int      false "Page size (max 50)"
// @Success      200  {object}  handlers.APIResponse "Search results"
// @Failure      400  {object}  handlers.APIResponse "Validation error"
// @Failure      500  {object}  handlers.APIResponse "Search failed"
// @Router       /search [get]
func (sh *SearchHandlers) Search(c *gin.Context) {
	query := c.Query("q")
	if query == "" {
		RespondWithAppError(c, apperrors.NewValidationError("Search query is required"))
		return
	}

	types := c.QueryArray("type")
	filters, filterErr := parseSearchFilters(c)
	if filterErr != nil {
		RespondWithAppError(c, apperrors.NewValidationError(filterErr.Error()))
		return
	}

	// v1.0.9 Day 9 — search.query span. Hot path: every search bar press
	// hits this. Query content is NOT recorded (PII / search history is
	// sensitive); only length + types so cardinality stays bounded.
	_, span := otel.Tracer(tracing.TracerName).Start(c.Request.Context(), "search.query",
		trace.WithAttributes(
			attribute.Int("search.query_length", len(query)),
			attribute.StringSlice("search.types", types),
			attribute.Bool("search.filtered", filters.HasAny()),
		),
	)
	defer span.End()

	results, err := sh.searchService.Search(query, types, filters)
	if err != nil {
		span.RecordError(err)
		span.SetStatus(codes.Error, "search failed")
		RespondWithAppError(c, apperrors.NewInternalErrorWrap("Search failed", err))
		return
	}

	RespondSuccess(c, http.StatusOK, results)
}

// parseSearchFilters reads the faceted-search query params and
// validates bounds. Returns a non-nil *SearchFilters with zero values
// for any param that wasn't sent ; service-side appendTrackFacets
// skips zero-valued fields silently.
//
// v1.0.9 W4 Day 18.
func parseSearchFilters(c *gin.Context) (*services.SearchFilters, error) {
	f := &services.SearchFilters{
		Genre:      c.Query("genre"),
		MusicalKey: c.Query("musical_key"),
	}
	if v := c.Query("bpm_min"); v != "" {
		n, err := strconv.Atoi(v)
		if err != nil || n < 1 || n > 999 {
			return nil, fmt.Errorf("bpm_min must be an integer in [1, 999]")
		}
		f.BPMMin = n
	}
	if v := c.Query("bpm_max"); v != "" {
		n, err := strconv.Atoi(v)
		if err != nil || n < 1 || n > 999 {
			return nil, fmt.Errorf("bpm_max must be an integer in [1, 999]")
		}
		f.BPMMax = n
	}
	if f.BPMMin > 0 && f.BPMMax > 0 && f.BPMMin > f.BPMMax {
		return nil, fmt.Errorf("bpm_min cannot exceed bpm_max")
	}
	if v := c.Query("year_from"); v != "" {
		n, err := strconv.Atoi(v)
		if err != nil || n < 1900 || n > 2100 {
			return nil, fmt.Errorf("year_from must be an integer in [1900, 2100]")
		}
		f.YearFrom = n
	}
	if v := c.Query("year_to"); v != "" {
		n, err := strconv.Atoi(v)
		if err != nil || n < 1900 || n > 2100 {
			return nil, fmt.Errorf("year_to must be an integer in [1900, 2100]")
		}
		f.YearTo = n
	}
	if f.YearFrom > 0 && f.YearTo > 0 && f.YearFrom > f.YearTo {
		return nil, fmt.Errorf("year_from cannot exceed year_to")
	}
	return f, nil
}

// Suggestions returns autocomplete suggestions for the search input
// @Summary      Search suggestions
// @Description  Lightweight autocomplete used by the search bar. Returns a small SearchResult subset (typically tracks + users + playlists), capped at `limit` (1..20, default 5). v1.0.9 item 1.6 — annotation added so orval can generate a typed client.
// @Tags         Search
// @Produce      json
// @Param        q     query string true  "Partial query (min 1 char)"
// @Param        limit query int    false "Max number of suggestions (1..20, default 5)"
// @Success      200  {object}  handlers.APIResponse "Suggestions"
// @Failure      400  {object}  handlers.APIResponse "Validation error"
// @Failure      500  {object}  handlers.APIResponse "Suggestions failed"
// @Router       /search/suggestions [get]
func (sh *SearchHandlers) Suggestions(c *gin.Context) {
	query := c.Query("q")
	if query == "" {
		RespondWithAppError(c, apperrors.NewValidationError("Query parameter 'q' is required"))
		return
	}
	limit := 5
	if l := c.Query("limit"); l != "" {
		if n, err := parseInt(l); err == nil && n > 0 && n <= 20 {
			limit = n
		}
	}
	results, err := sh.searchService.Suggestions(query, limit)
	if err != nil {
		RespondWithAppError(c, apperrors.NewInternalErrorWrap("Suggestions failed", err))
		return
	}
	RespondSuccess(c, http.StatusOK, results)
}

func parseInt(s string) (int, error) {
	return strconv.Atoi(s)
}