package app

import (
	"context"
	"database/sql"
	"encoding/json"
	"fmt"
	"net/http"
	"strconv"
	"strings"
	"time"
)

// Adoption is an information service, not a marketplace: there is no price
// field anywhere in it, and anything in the free text that smells like one
// sends the listing to a human instead of straight onto the shelf.

type adoptionView struct {
	ID           int64    `json:"id"`
	PetID        int64    `json:"petId"`
	OwnerUserID  int64    `json:"ownerUserId"`
	OwnerName    string   `json:"ownerName"`
	PetName      string   `json:"petName"`
	Species      string   `json:"species"`
	SpeciesLabel string   `json:"speciesLabel"`
	Breed        string   `json:"breed"`
	Gender       int      `json:"gender"`
	AgeMonths    int      `json:"ageMonths"`
	Neutered     bool     `json:"neutered"`
	VaccinatedAt string   `json:"vaccinatedAt,omitempty"`
	Avatar       string   `json:"avatar"`
	Photos       []string `json:"photos"`
	CityName     string   `json:"cityName"`
	Reason       string   `json:"reason"`
	Requirements string   `json:"requirements"`
	Status       int      `json:"status"`
	Moderation   int      `json:"moderationStatus"`
	Applications int      `json:"applicationCount"`
	Mine         bool     `json:"mine"`
	Applied      bool     `json:"applied"`
	CreatedAt    string   `json:"createdAt"`
}

// The questionnaire is the only real filter a giver has. Keeping the questions
// server-side means every listing asks the same things and the answers stay
// comparable.
var adoptionQuestions = []struct {
	Key   string `json:"key"`
	Label string `json:"label"`
}{
	{"housing", "居住情况（自有/租住，房东是否允许养宠）"},
	{"members", "家人或室友是否都同意"},
	{"pets", "家里是否已有其他宠物"},
	{"experience", "过往养宠经验"},
	{"followup", "是否接受送出后的回访"},
}

func (a *App) adoptionReviewReason(ctx context.Context, ownerID int64, text string) string {
	// 统一词库优先；配置里那份旧词表留着兜底，免得词库被清空后送养就没人看了。
	if word, _ := a.matchKeyword(ctx, "adoption", text); word != "" {
		return "文案命中敏感词：" + word
	}
	words := strings.Split(a.configPlain(ctx, "pet.adoption_review_words", ""), ",")
	lowered := strings.ToLower(text)
	for _, word := range words {
		word = strings.TrimSpace(word)
		if word != "" && strings.Contains(lowered, strings.ToLower(word)) {
			return "文案命中敏感词：" + word
		}
	}
	// Someone giving away a litter every month is a breeder, not an owner in
	// trouble. The window and threshold are both configurable.
	days := a.configInt(ctx, "pet.adoption_batch_days", 90)
	limit := a.configInt(ctx, "pet.adoption_batch_limit", 3)
	if days > 0 && limit > 0 {
		var recent int
		_ = a.db.QueryRowContext(ctx, `SELECT COUNT(*) FROM pet_adoptions WHERE owner_user_id=? AND deleted_at IS NULL AND created_at>DATE_SUB(NOW(3),INTERVAL ? DAY)`, ownerID, days).Scan(&recent)
		if recent >= limit {
			return fmt.Sprintf("%d 天内已发布 %d 条送养", days, recent)
		}
	}
	return ""
}

func (a *App) createAdoption(w http.ResponseWriter, r *http.Request) {
	if !a.configBool(r.Context(), "pet.adoption_enabled", true) {
		fail(w, http.StatusForbidden, 30002, "送养功能暂未开放")
		return
	}
	var req struct {
		PetID        int64  `json:"petId"`
		CityCode     string `json:"cityCode"`
		CityName     string `json:"cityName"`
		Reason       string `json:"reason"`
		Requirements string `json:"requirements"`
	}
	if decode(r, &req) != nil || req.PetID == 0 {
		fail(w, http.StatusBadRequest, 20001, "送养信息格式错误")
		return
	}
	req.Reason = strings.TrimSpace(req.Reason)
	req.Requirements = strings.TrimSpace(req.Requirements)
	req.CityName = strings.TrimSpace(req.CityName)
	if len([]rune(req.Reason)) < 10 || len([]rune(req.Reason)) > 500 {
		fail(w, http.StatusBadRequest, 20001, "请说明送养原因，10 到 500 字")
		return
	}
	if len([]rune(req.Requirements)) > 500 || len([]rune(req.CityName)) > 50 {
		fail(w, http.StatusBadRequest, 20001, "内容过长")
		return
	}
	// The listing inherits its facts from the profile, so the profile has to be
	// complete first: photos to look at, and a vaccination record to trust.
	var vaccinated sql.NullTime
	var photos int
	if err := a.db.QueryRowContext(r.Context(), `SELECT p.vaccinated_at,(SELECT COUNT(*) FROM pet_media m WHERE m.pet_id=p.id)
		FROM pets p WHERE p.id=? AND p.owner_user_id=? AND p.status=1 AND p.deleted_at IS NULL`, req.PetID, current(r).ID).Scan(&vaccinated, &photos); err != nil {
		fail(w, http.StatusNotFound, 30001, "宠物不存在")
		return
	}
	if minPhotos := a.configInt(r.Context(), "pet.adoption_min_photos", 3); photos < minPhotos {
		fail(w, http.StatusBadRequest, 20001, fmt.Sprintf("发布送养前请至少上传 %d 张宠物照片", minPhotos))
		return
	}
	if !vaccinated.Valid {
		fail(w, http.StatusBadRequest, 20001, "请先在宠物档案中填写免疫日期")
		return
	}
	var existing int
	_ = a.db.QueryRowContext(r.Context(), `SELECT COUNT(*) FROM pet_adoptions WHERE pet_id=? AND status=1 AND deleted_at IS NULL`, req.PetID).Scan(&existing)
	if existing > 0 {
		fail(w, http.StatusBadRequest, 20001, "这只宠物已经在送养中")
		return
	}
	reviewReason := a.adoptionReviewReason(r.Context(), current(r).ID, req.Reason+" "+req.Requirements)
	result, err := a.db.ExecContext(r.Context(), `INSERT INTO pet_adoptions(pet_id,owner_user_id,city_code,city_name,reason,requirements,review_reason)
		VALUES(?,?,?,?,?,?,?)`, req.PetID, current(r).ID, strings.TrimSpace(req.CityCode), req.CityName, req.Reason, req.Requirements, reviewReason)
	if err != nil {
		fail(w, http.StatusInternalServerError, 50001, "发布失败")
		return
	}
	id, _ := result.LastInsertId()
	reply(w, map[string]any{"id": id, "pendingReview": true, "reviewReason": reviewReason})
}

const adoptionColumns = `a.id,a.pet_id,a.owner_user_id,owner.nickname,a.city_name,a.reason,a.requirements,a.status,a.moderation_status,a.application_count,a.created_at,
	p.name,p.species,p.breed,p.gender,p.birthday,p.neutered,p.vaccinated_at,p.avatar_url`

func (a *App) scanAdoptions(ctx context.Context, rows *sql.Rows, viewer int64) []adoptionView {
	items := []adoptionView{}
	ids := []any{}
	placeholders := []string{}
	for rows.Next() {
		var item adoptionView
		var birthday, vaccinated sql.NullTime
		var created time.Time
		var neutered int
		if rows.Scan(&item.ID, &item.PetID, &item.OwnerUserID, &item.OwnerName, &item.CityName, &item.Reason,
			&item.Requirements, &item.Status, &item.Moderation, &item.Applications, &created,
			&item.PetName, &item.Species, &item.Breed, &item.Gender, &birthday, &neutered, &vaccinated, &item.Avatar) != nil {
			continue
		}
		item.SpeciesLabel = petSpecies[item.Species]
		item.Neutered = neutered == 1
		if birthday.Valid {
			item.AgeMonths = monthsSince(birthday.Time)
		}
		if vaccinated.Valid {
			item.VaccinatedAt = vaccinated.Time.Format("2006-01-02")
		}
		item.CreatedAt = created.Format(time.RFC3339)
		item.Mine = item.OwnerUserID == viewer
		item.Photos = []string{}
		items = append(items, item)
		ids = append(ids, item.PetID)
		placeholders = append(placeholders, "?")
	}
	if len(ids) == 0 {
		return items
	}
	mediaRows, err := a.db.QueryContext(ctx, `SELECT pet_id,media_url FROM pet_media WHERE pet_id IN (`+strings.Join(placeholders, ",")+`) ORDER BY pet_id,sort_order,id`, ids...)
	if err == nil {
		defer mediaRows.Close()
		for mediaRows.Next() {
			var petID int64
			var url string
			if mediaRows.Scan(&petID, &url) != nil {
				continue
			}
			for index := range items {
				if items[index].PetID == petID {
					items[index].Photos = append(items[index].Photos, url)
				}
			}
		}
	}
	// One query tells the reader which listings they already applied to, so the
	// list can show "已申请" without a request per card.
	appliedRows, err := a.db.QueryContext(ctx, `SELECT adoption_id FROM pet_adoption_applications WHERE applicant_user_id=? AND status IN (0,1)`, viewer)
	if err == nil {
		defer appliedRows.Close()
		applied := map[int64]bool{}
		for appliedRows.Next() {
			var id int64
			if appliedRows.Scan(&id) == nil {
				applied[id] = true
			}
		}
		for index := range items {
			items[index].Applied = applied[items[index].ID]
		}
	}
	return items
}

func (a *App) adoptions(w http.ResponseWriter, r *http.Request) {
	_, size, offset := pageOptions(r)
	where := " WHERE a.deleted_at IS NULL"
	args := []any{}
	if strings.TrimSpace(r.URL.Query().Get("mine")) == "1" {
		where += " AND a.owner_user_id=?"
		args = append(args, current(r).ID)
	} else {
		// The shelf only carries approved, still-open listings.
		where += " AND a.status=1 AND a.moderation_status=1"
		if city := strings.TrimSpace(r.URL.Query().Get("cityCode")); city != "" {
			where += " AND a.city_code=?"
			args = append(args, city)
		}
		if species := strings.TrimSpace(r.URL.Query().Get("species")); species != "" {
			where += " AND p.species=?"
			args = append(args, species)
		}
	}
	query := `SELECT ` + adoptionColumns + ` FROM pet_adoptions a
		JOIN pets p ON p.id=a.pet_id JOIN user_profiles owner ON owner.user_id=a.owner_user_id` + where +
		` ORDER BY a.id DESC LIMIT ? OFFSET ?`
	rows, err := a.db.QueryContext(r.Context(), query, append(args, size+1, offset)...)
	if err != nil {
		fail(w, http.StatusInternalServerError, 50001, "查询送养信息失败")
		return
	}
	defer rows.Close()
	items := a.scanAdoptions(r.Context(), rows, current(r).ID)
	hasMore := len(items) > size
	if hasMore {
		items = items[:size]
	}
	reply(w, map[string]any{"items": items, "hasMore": hasMore, "questions": adoptionQuestions})
}

func (a *App) adoptionDetail(w http.ResponseWriter, r *http.Request) {
	id, err := pathID(r)
	if err != nil {
		fail(w, http.StatusBadRequest, 20001, "编号无效")
		return
	}
	rows, queryErr := a.db.QueryContext(r.Context(), `SELECT `+adoptionColumns+` FROM pet_adoptions a
		JOIN pets p ON p.id=a.pet_id JOIN user_profiles owner ON owner.user_id=a.owner_user_id
		WHERE a.id=? AND a.deleted_at IS NULL AND (a.owner_user_id=? OR (a.status<>0 AND a.moderation_status=1))`, id, current(r).ID)
	if queryErr != nil {
		fail(w, http.StatusInternalServerError, 50001, "查询失败")
		return
	}
	defer rows.Close()
	items := a.scanAdoptions(r.Context(), rows, current(r).ID)
	if len(items) == 0 {
		fail(w, http.StatusNotFound, 30001, "送养信息不存在")
		return
	}
	view := map[string]any{"adoption": items[0], "questions": adoptionQuestions}
	// Answers are private to the giver: they contain where a stranger lives.
	if items[0].Mine {
		applications, _ := a.adoptionApplications(r.Context(), id)
		view["applications"] = applications
		var note string
		_ = a.db.QueryRowContext(r.Context(), `SELECT moderation_note FROM pet_adoptions WHERE id=?`, id).Scan(&note)
		view["moderationNote"] = note
	}
	reply(w, view)
}

func (a *App) adoptionApplications(ctx context.Context, adoptionID int64) ([]map[string]any, error) {
	rows, err := a.db.QueryContext(ctx, `SELECT ap.id,ap.applicant_user_id,profile.nickname,profile.avatar_url,ap.answers_json,ap.message,ap.status,ap.created_at
		FROM pet_adoption_applications ap JOIN user_profiles profile ON profile.user_id=ap.applicant_user_id
		WHERE ap.adoption_id=? ORDER BY ap.id DESC`, adoptionID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	items := []map[string]any{}
	for rows.Next() {
		var id, userID int64
		var nickname, avatar, answers, message string
		var status int
		var created time.Time
		if rows.Scan(&id, &userID, &nickname, &avatar, &answers, &message, &status, &created) != nil {
			continue
		}
		parsed := map[string]string{}
		_ = json.Unmarshal([]byte(answers), &parsed)
		items = append(items, map[string]any{
			"id": id, "userId": userID, "nickname": nickname, "avatar": avatarThumbnailURL(avatar),
			"answers": parsed, "message": message, "status": status, "createdAt": created.Format(time.RFC3339),
		})
	}
	return items, nil
}

func (a *App) applyAdoption(w http.ResponseWriter, r *http.Request) {
	id, err := pathID(r)
	if err != nil {
		fail(w, http.StatusBadRequest, 20001, "编号无效")
		return
	}
	var req struct {
		Answers map[string]string `json:"answers"`
		Message string            `json:"message"`
	}
	if decode(r, &req) != nil {
		fail(w, http.StatusBadRequest, 20001, "申请格式错误")
		return
	}
	for _, question := range adoptionQuestions {
		if strings.TrimSpace(req.Answers[question.Key]) == "" {
			fail(w, http.StatusBadRequest, 20001, "请回答："+question.Label)
			return
		}
		if len([]rune(req.Answers[question.Key])) > 200 {
			fail(w, http.StatusBadRequest, 20001, "每个回答最多 200 字")
			return
		}
	}
	var owner int64
	var status, moderation int
	if a.db.QueryRowContext(r.Context(), `SELECT owner_user_id,status,moderation_status FROM pet_adoptions WHERE id=? AND deleted_at IS NULL`, id).Scan(&owner, &status, &moderation) != nil {
		fail(w, http.StatusNotFound, 30001, "送养信息不存在")
		return
	}
	if owner == current(r).ID {
		fail(w, http.StatusBadRequest, 20001, "不能申请领养自己送养的宠物")
		return
	}
	if status != 1 || moderation != 1 {
		fail(w, http.StatusBadRequest, 20001, "这条送养信息已经不接受申请")
		return
	}
	answers, _ := json.Marshal(req.Answers)
	tx, err := a.db.BeginTx(r.Context(), nil)
	if err != nil {
		fail(w, http.StatusInternalServerError, 50001, "提交失败")
		return
	}
	defer func() { _ = tx.Rollback() }()
	if _, err = tx.ExecContext(r.Context(), `INSERT INTO pet_adoption_applications(adoption_id,applicant_user_id,answers_json,message)
		VALUES(?,?,?,?)`, id, current(r).ID, string(answers), strings.TrimSpace(req.Message)); err != nil {
		fail(w, http.StatusBadRequest, 20001, "你已经申请过这条送养信息")
		return
	}
	if _, err = tx.ExecContext(r.Context(), `UPDATE pet_adoptions SET application_count=application_count+1 WHERE id=?`, id); err != nil {
		fail(w, http.StatusInternalServerError, 50001, "提交失败")
		return
	}
	if tx.Commit() != nil {
		fail(w, http.StatusInternalServerError, 50001, "提交失败")
		return
	}
	a.notifyUser(r.Context(), owner, "system", "收到领养申请", "有人申请领养你送养的宠物，去看看是否合适", "adoption", id)
	reply(w, map[string]bool{"success": true})
}

// decideAdoption is where a listing turns into a real handover: choosing one
// applicant closes the listing, declines the rest and schedules the follow-ups.
func (a *App) decideAdoption(w http.ResponseWriter, r *http.Request) {
	id, err := pathID(r)
	if err != nil {
		fail(w, http.StatusBadRequest, 20001, "编号无效")
		return
	}
	var req struct {
		ApplicationID int64  `json:"applicationId"`
		Action        string `json:"action"`
	}
	if decode(r, &req) != nil || req.ApplicationID == 0 {
		fail(w, http.StatusBadRequest, 20001, "参数错误")
		return
	}
	var owner int64
	var status int
	if a.db.QueryRowContext(r.Context(), `SELECT owner_user_id,status FROM pet_adoptions WHERE id=? AND deleted_at IS NULL`, id).Scan(&owner, &status) != nil || owner != current(r).ID {
		fail(w, http.StatusNotFound, 30001, "送养信息不存在")
		return
	}
	var applicant int64
	if a.db.QueryRowContext(r.Context(), `SELECT applicant_user_id FROM pet_adoption_applications WHERE id=? AND adoption_id=?`, req.ApplicationID, id).Scan(&applicant) != nil {
		fail(w, http.StatusNotFound, 30001, "申请不存在")
		return
	}
	if req.Action == "decline" {
		if _, err = a.db.ExecContext(r.Context(), `UPDATE pet_adoption_applications SET status=2,decided_at=NOW(3) WHERE id=? AND status=0`, req.ApplicationID); err != nil {
			fail(w, http.StatusInternalServerError, 50001, "操作失败")
			return
		}
		a.notifyUser(r.Context(), applicant, "system", "领养申请未通过", "送养人这次选择了其他领养人，可以再看看别的宠物", "adoption", id)
		reply(w, map[string]bool{"success": true})
		return
	}
	if status != 1 {
		fail(w, http.StatusBadRequest, 20001, "这条送养信息已经结束")
		return
	}
	tx, err := a.db.BeginTx(r.Context(), nil)
	if err != nil {
		fail(w, http.StatusInternalServerError, 50001, "操作失败")
		return
	}
	defer func() { _ = tx.Rollback() }()
	if _, err = tx.ExecContext(r.Context(), `UPDATE pet_adoption_applications SET status=1,decided_at=NOW(3) WHERE id=?`, req.ApplicationID); err != nil {
		fail(w, http.StatusInternalServerError, 50001, "操作失败")
		return
	}
	if _, err = tx.ExecContext(r.Context(), `UPDATE pet_adoption_applications SET status=2,decided_at=NOW(3) WHERE adoption_id=? AND id<>? AND status=0`, id, req.ApplicationID); err != nil {
		fail(w, http.StatusInternalServerError, 50001, "操作失败")
		return
	}
	if _, err = tx.ExecContext(r.Context(), `UPDATE pet_adoptions SET status=2,adopter_user_id=?,completed_at=NOW(3) WHERE id=?`, applicant, id); err != nil {
		fail(w, http.StatusInternalServerError, 50001, "操作失败")
		return
	}
	// Follow-ups are created now, with the handover, so nothing has to remember
	// to create them later.
	for _, day := range strings.Split(a.configPlain(r.Context(), "pet.adoption_followup_days", "30,90"), ",") {
		days, convErr := strconv.Atoi(strings.TrimSpace(day))
		if convErr != nil || days <= 0 {
			continue
		}
		if _, err = tx.ExecContext(r.Context(), `INSERT INTO pet_adoption_followups(adoption_id,adopter_user_id,due_at) VALUES(?,?,DATE_ADD(NOW(3),INTERVAL ? DAY))`, id, applicant, days); err != nil {
			fail(w, http.StatusInternalServerError, 50001, "操作失败")
			return
		}
	}
	if tx.Commit() != nil {
		fail(w, http.StatusInternalServerError, 50001, "操作失败")
		return
	}
	a.notifyUser(r.Context(), applicant, "system", "领养申请通过", "送养人选择了你，请尽快联系并当面确认", "adoption", id)
	reply(w, map[string]bool{"success": true})
}

func (a *App) closeAdoption(w http.ResponseWriter, r *http.Request) {
	id, err := pathID(r)
	if err != nil {
		fail(w, http.StatusBadRequest, 20001, "编号无效")
		return
	}
	result, err := a.db.ExecContext(r.Context(), `UPDATE pet_adoptions SET status=0 WHERE id=? AND owner_user_id=? AND status=1`, id, current(r).ID)
	if err != nil {
		fail(w, http.StatusInternalServerError, 50001, "操作失败")
		return
	}
	if affected, _ := result.RowsAffected(); affected == 0 {
		fail(w, http.StatusNotFound, 30001, "送养信息不存在或已结束")
		return
	}
	reply(w, map[string]bool{"success": true})
}

func (a *App) myAdoptionFollowups(w http.ResponseWriter, r *http.Request) {
	rows, err := a.db.QueryContext(r.Context(), `SELECT f.id,f.adoption_id,f.due_at,f.submitted_at,f.content,f.media_json,p.name,p.avatar_url
		FROM pet_adoption_followups f JOIN pet_adoptions a ON a.id=f.adoption_id JOIN pets p ON p.id=a.pet_id
		WHERE f.adopter_user_id=? ORDER BY f.submitted_at IS NOT NULL,f.due_at`, current(r).ID)
	if err != nil {
		fail(w, http.StatusInternalServerError, 50001, "查询回访失败")
		return
	}
	defer rows.Close()
	items := []map[string]any{}
	for rows.Next() {
		var id, adoptionID int64
		var due time.Time
		var submitted sql.NullTime
		var content, petName, avatar string
		var mediaJSON sql.NullString
		if rows.Scan(&id, &adoptionID, &due, &submitted, &content, &mediaJSON, &petName, &avatar) != nil {
			continue
		}
		media := []string{}
		if mediaJSON.Valid {
			_ = json.Unmarshal([]byte(mediaJSON.String), &media)
		}
		items = append(items, map[string]any{
			"id": id, "adoptionId": adoptionID, "dueAt": due.Format(time.RFC3339),
			"submitted": submitted.Valid, "content": content, "media": media, "petName": petName, "avatar": avatar,
			"overdue": !submitted.Valid && time.Now().After(due),
		})
	}
	reply(w, map[string]any{"items": items})
}

func (a *App) submitAdoptionFollowup(w http.ResponseWriter, r *http.Request) {
	id, err := pathID(r)
	if err != nil {
		fail(w, http.StatusBadRequest, 20001, "编号无效")
		return
	}
	var req struct {
		Content string   `json:"content"`
		Media   []string `json:"media"`
	}
	if decode(r, &req) != nil {
		fail(w, http.StatusBadRequest, 20001, "回访格式错误")
		return
	}
	req.Content = strings.TrimSpace(req.Content)
	if req.Content == "" && len(req.Media) == 0 {
		fail(w, http.StatusBadRequest, 20001, "写一句近况，或者上传一张照片")
		return
	}
	if len([]rune(req.Content)) > 500 || len(req.Media) > 9 {
		fail(w, http.StatusBadRequest, 20001, "内容过长或照片过多")
		return
	}
	for _, item := range req.Media {
		if !validMessageMediaURL(item, a.config.Environment == "production") {
			fail(w, http.StatusBadRequest, 20001, "照片地址无效")
			return
		}
	}
	media, _ := json.Marshal(req.Media)
	result, err := a.db.ExecContext(r.Context(), `UPDATE pet_adoption_followups SET content=?,media_json=?,submitted_at=NOW(3)
		WHERE id=? AND adopter_user_id=? AND submitted_at IS NULL`, req.Content, string(media), id, current(r).ID)
	if err != nil {
		fail(w, http.StatusInternalServerError, 50001, "提交失败")
		return
	}
	if affected, _ := result.RowsAffected(); affected == 0 {
		fail(w, http.StatusNotFound, 30001, "回访不存在或已提交")
		return
	}
	reply(w, map[string]bool{"success": true})
}