package main

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

	"github.com/gin-gonic/gin"
	"gorm.io/gorm"
)

// People (subjects + unnamed face clusters), scoped to the caller's
// BasePath the same way handleLabels scopes labels: proxy PhotoPrism's
// list, then one SQL pass over the caller's slice of the library to
// recompute counts and drop entries with nothing in scope.
//
// PhotoPrism CE treats subjects and face clusters as library-wide
// metadata (like albums and labels) — scoping here controls what each
// user *sees*, while the underlying entities stay shared.

// PpSubjectLite mirrors the fields the web client consumes from
// PhotoPrism's /api/v1/subjects rows.
type PpSubjectLite struct {
	UID        string `json:"UID"`
	Type       string `json:"Type"`
	Slug       string `json:"Slug"`
	Name       string `json:"Name"`
	Alias      string `json:"Alias"`
	Favorite   bool   `json:"Favorite"`
	Private    bool   `json:"Private"`
	Excluded   bool   `json:"Excluded"`
	Hidden     bool   `json:"Hidden"`
	PhotoCount int    `json:"PhotoCount"`
	FileCount  int    `json:"FileCount"`
	Thumb      string `json:"Thumb"`
}

// handleSubjects proxies PhotoPrism's /api/v1/subjects and post-filters
// per-subject photo counts to the caller's BasePath, dropping subjects
// whose faces never appear in the caller's photos.
//
// Route: GET /api/sidecar/subjects  (behind requireSession)
func handleSubjects(pp *ppClient, ppDb *gorm.DB) gin.HandlerFunc {
	return func(c *gin.Context) {
		token := ctxToken(c)
		basePath := ctxBasePath(c)

		query := c.Request.URL.RawQuery
		resp, err := pp.call(c.Request.Context(), http.MethodGet, "/api/v1/subjects?"+query, token, nil)
		if err != nil || !resp.OK {
			c.JSON(http.StatusBadGateway, gin.H{"error": "upstream subjects request failed"})
			return
		}
		var subjects []PpSubjectLite
		if err := json.Unmarshal(resp.Body, &subjects); err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to parse subjects"})
			return
		}

		if basePath == "" || ppDb == nil {
			c.JSON(http.StatusOK, subjects)
			return
		}

		// One query: per-subject photo count + a representative face-crop
		// thumb, restricted to the caller's path subtree. The join chain is
		// markers → files → photos, matching how PhotoPrism binds a face to
		// a picture.
		type subjStat struct {
			SubjUID string `gorm:"column:subj_uid"`
			Cnt     int64  `gorm:"column:cnt"`
			Thumb   string `gorm:"column:thumb"`
		}
		var stats []subjStat
		if err := ppDb.Raw(`
			SELECT m.subj_uid AS subj_uid,
			       COUNT(DISTINCT p.id) AS cnt,
			       SUBSTRING_INDEX(GROUP_CONCAT(m.thumb ORDER BY m.size DESC SEPARATOR 0x1f), 0x1f, 1) AS thumb
			FROM   markers m
			JOIN   files  f ON f.file_uid  = m.file_uid  AND f.file_missing = 0
			JOIN   photos p ON p.photo_uid = f.photo_uid AND p.deleted_at IS NULL
			WHERE  m.marker_type = 'face'
			  AND  m.marker_invalid = 0
			  AND  m.subj_uid IS NOT NULL AND m.subj_uid <> ''
			  AND  (p.photo_path = ? OR p.photo_path LIKE ?)
			GROUP  BY m.subj_uid
		`, basePath, basePath+"/%").Scan(&stats).Error; err != nil {
			c.JSON(http.StatusBadGateway, gin.H{"error": "subject stats query failed"})
			return
		}

		cntMap := make(map[string]int64, len(stats))
		thumbMap := make(map[string]string, len(stats))
		for _, s := range stats {
			cntMap[s.SubjUID] = s.Cnt
			thumbMap[s.SubjUID] = s.Thumb
		}

		filtered := make([]PpSubjectLite, 0, len(stats))
		for _, s := range subjects {
			cnt, ok := cntMap[s.UID]
			if !ok || cnt == 0 {
				continue
			}
			s.PhotoCount = int(cnt)
			if th := thumbMap[s.UID]; th != "" {
				s.Thumb = th
			}
			filtered = append(filtered, s)
		}
		c.JSON(http.StatusOK, filtered)
	}
}

// unnamedFaceCluster is one face cluster PhotoPrism has detected but
// nobody has named yet. Naming happens the same way PhotoPrism's own
// People→New tab does it: PUT /api/v1/markers/<markerUid> with
// {Name, SubjSrc:"manual"} — PhotoPrism then creates the Subject and
// propagates it across the cluster (verified against
// internal/api/markers.go + frontend/src/model/face.js).
type unnamedFaceCluster struct {
	FaceID string `json:"faceId" gorm:"column:face_id"`
	// Photos under the caller's scope carrying this face.
	Count int64 `json:"count" gorm:"column:cnt"`
	// Marker crop hash — renders via /api/v1/t/<thumb>/<token>/tile_320.
	Thumb string `json:"thumb" gorm:"column:thumb"`
	// Representative marker (largest face in scope) — the PUT target
	// when the user names this cluster.
	MarkerUID string `json:"markerUid" gorm:"column:marker_uid"`
}

// handleUnnamedFaces lists face clusters awaiting a name, scoped to the
// caller's BasePath (admins with no BasePath see the whole library).
// Ordered by in-scope photo count so the most prominent people surface
// first.
//
// Route: GET /api/sidecar/faces/unnamed  (behind requireSession)
func handleUnnamedFaces(ppDb *gorm.DB) gin.HandlerFunc {
	return func(c *gin.Context) {
		if ppDb == nil {
			c.JSON(http.StatusOK, gin.H{"clusters": []unnamedFaceCluster{}})
			return
		}
		basePath := ctxBasePath(c)

		where := ""
		args := []any{}
		if basePath != "" {
			where = "AND (p.photo_path = ? OR p.photo_path LIKE ?)"
			args = []any{basePath, basePath + "/%"}
		}
		var clusters []unnamedFaceCluster
		if err := ppDb.Raw(`
			SELECT m.face_id AS face_id,
			       COUNT(DISTINCT p.id) AS cnt,
			       SUBSTRING_INDEX(GROUP_CONCAT(m.thumb ORDER BY m.size DESC SEPARATOR 0x1f), 0x1f, 1) AS thumb,
			       SUBSTRING_INDEX(GROUP_CONCAT(m.marker_uid ORDER BY m.size DESC SEPARATOR 0x1f), 0x1f, 1) AS marker_uid
			FROM   markers m
			JOIN   files  f  ON f.file_uid  = m.file_uid  AND f.file_missing = 0
			JOIN   photos p  ON p.photo_uid = f.photo_uid AND p.deleted_at IS NULL
			JOIN   faces  fc ON fc.id = m.face_id AND fc.face_hidden = 0
			WHERE  m.marker_type = 'face'
			  AND  m.marker_invalid = 0
			  AND  (m.subj_uid IS NULL OR m.subj_uid = '')
			  AND  m.face_id <> ''
			  `+where+`
			GROUP  BY m.face_id
			ORDER  BY cnt DESC
			LIMIT  60
		`, args...).Scan(&clusters).Error; err != nil {
			c.JSON(http.StatusBadGateway, gin.H{"error": "face cluster query failed"})
			return
		}
		if clusters == nil {
			clusters = []unnamedFaceCluster{}
		}
		c.JSON(http.StatusOK, gin.H{"clusters": clusters})
	}
}