package controllers

import (
	"sort"
	"strings"
	"time"

	"server/models"
)

// BackendErpReportController 进销存报表：购销汇总、收发存、毛利、客户RFM、经营看板
//
// 统计口径全部来自「已生效」单据与库存流水，草稿/审批中/作废不参与，
// 这样报表数字与账务（往来账、库存结存）永远一致。
type BackendErpReportController struct {
	BackendErpBaseController
}

// reportRange 解析日期区间，默认当月
func (c *BackendErpReportController) reportRange() (time.Time, time.Time) {
	from, to := erpMonthRange(0)
	if d := strings.TrimSpace(c.GetString("date_from")); d != "" {
		if t, e := time.ParseInLocation("2006-01-02", d, time.Local); e == nil {
			from = t
		}
	}
	if d := strings.TrimSpace(c.GetString("date_to")); d != "" {
		if t, e := time.ParseInLocation("2006-01-02", d, time.Local); e == nil {
			to = t.AddDate(0, 0, 1)
		}
	}
	return from, to
}

func erpMonthRange(offsetMonths int) (time.Time, time.Time) {
	now := time.Now()
	first := time.Date(now.Year(), now.Month()+time.Month(offsetMonths), 1, 0, 0, 0, 0, time.Local)
	return first, first.AddDate(0, 1, 0)
}

// approvedDocIDs 区间内已生效单据ID（按类型）
func erpApprovedDocIDs(tid string, docTypes []string, from, to time.Time, partnerID uint64) []uint64 {
	qs := models.Orm.QueryTable(new(models.ErpDocument)).
		Filter("tenant_id", tid).
		Filter("doc_type__in", docTypes).
		Filter("status", models.ErpDocStatusApproved).
		Filter("delete_time__isnull", true).
		Filter("biz_date__gte", from).Filter("biz_date__lt", to)
	if partnerID > 0 {
		qs = qs.Filter("partner_id", partnerID)
	}
	var rows []models.ErpDocument
	_, _ = qs.All(&rows, "id")
	ids := make([]uint64, 0, len(rows))
	for _, r := range rows {
		ids = append(ids, r.ID)
	}
	return ids
}

func erpItemsByDocs(tid string, docIDs []uint64) []models.ErpDocumentItem {
	if len(docIDs) == 0 {
		return nil
	}
	var out []models.ErpDocumentItem
	_, _ = models.Orm.QueryTable(new(models.ErpDocumentItem)).
		Filter("tenant_id", tid).Filter("doc_id__in", docIDs).All(&out)
	return out
}

// PurchaseSummary GET /backend/erp/report/purchase 采购汇总（dimension=product|supplier|month）
func (c *BackendErpReportController) PurchaseSummary() {
	cl, err := c.claims()
	if c.denied(err) {
		return
	}
	tid := c.tid(cl)
	from, to := c.reportRange()
	group := erpReportDimension(c.GetString("dimension"))
	items, docPartner, returnItems := erpSummaryDocs(tid, models.ErpDocPurchaseIn,
		models.ErpDocPurchaseReturn, from, to, erpUintParam(c.GetString("partner_id")))
	c.ok(erpSummaryReportData(group, items, docPartner, returnItems))
}

// SalesSummary GET /backend/erp/report/sales 销售汇总（dimension=product|customer|month）
func (c *BackendErpReportController) SalesSummary() {
	cl, err := c.claims()
	if c.denied(err) {
		return
	}
	tid := c.tid(cl)
	from, to := c.reportRange()
	group := erpReportDimension(c.GetString("dimension"))
	items, docPartner, returnItems := erpSummaryDocs(tid, models.ErpDocSalesOut,
		models.ErpDocSalesReturn, from, to, erpUintParam(c.GetString("partner_id")))
	c.ok(erpSummaryReportData(group, items, docPartner, returnItems))
}

// Rank GET /backend/erp/report/rank 热销/滞销排行
func (c *BackendErpReportController) Rank() {
	cl, err := c.claims()
	if c.denied(err) {
		return
	}
	from, to := c.reportRange()
	top, _ := c.GetInt("top", 10)
	asc := strings.TrimSpace(c.GetString("order")) == "asc"
	data, code, msg := erpSalesRankCore(erpNewActor(cl), from, to, top, asc)
	if msg != "" {
		c.fail(code, code, msg)
		return
	}
	c.ok(data)
}

// StockMove GET /backend/erp/report/stockmove 收发存汇总表
// 期末取自库存结存，本期收发取自库存流水，期初=期末-(入-出)，保证与账实一致。
func (c *BackendErpReportController) StockMove() {
	cl, err := c.claims()
	if c.denied(err) {
		return
	}
	from, to := c.reportRange()
	page, pageSize := c.pageArgs()
	list, total, summary, code, msg := erpStockMoveCore(
		erpNewActor(cl), from, to,
		erpUintParam(c.GetString("warehouse_id")),
		c.GetString("keyword"),
		page, pageSize,
	)
	if msg != "" {
		c.fail(code, code, msg)
		return
	}
	c.Data["json"] = map[string]interface{}{
		"code": 200, "msg": "success",
		"data": map[string]interface{}{
			"list": list, "total": total, "page": page, "pageSize": pageSize,
			"summary": summary,
		},
	}
	_ = c.ServeJSON()
}

// Profit GET /backend/erp/report/profit 毛利分析：收入=销售出库金额-销售退货金额，
// 成本取库存流水的实际出库成本（移动加权），不受手工录入影响。
func (c *BackendErpReportController) Profit() {
	cl, err := c.claims()
	if c.denied(err) {
		return
	}
	from, to := c.reportRange()
	data, code, msg := erpProfitCore(erpNewActor(cl), from, to)
	if msg != "" {
		c.fail(code, code, msg)
		return
	}
	c.ok(data)
}

// RFM GET /backend/erp/report/rfm 客户价值分层（R最近购买/F频次/M金额）
func (c *BackendErpReportController) RFM() {
	cl, err := c.claims()
	if c.denied(err) {
		return
	}
	tid := c.tid(cl)
	var docs []models.ErpDocument
	_, _ = models.Orm.QueryTable(new(models.ErpDocument)).
		Filter("tenant_id", tid).
		Filter("doc_type__in", []string{models.ErpDocSalesOut, models.ErpDocSalesReturn}).
		Filter("status", models.ErpDocStatusApproved).
		Filter("delete_time__isnull", true).All(&docs)
	now := time.Now()
	type row struct {
		CustomerID   uint64  `json:"customer_id"`
		CustomerName string  `json:"customer_name"`
		RDays        int     `json:"r_days"`
		FCount       int     `json:"f_count"`
		MAmount      float64 `json:"m_amount"`
		RScore       int     `json:"r_score"`
		FScore       int     `json:"f_score"`
		MScore       int     `json:"m_score"`
		Segment      string  `json:"segment"`
		LastDate     string  `json:"last_date"`
	}
	agg := map[uint64]*row{}
	for _, d := range docs {
		if d.PartnerID == 0 {
			continue
		}
		r := agg[d.PartnerID]
		if r == nil {
			r = &row{CustomerID: d.PartnerID, CustomerName: d.PartnerName, RDays: 99999}
			agg[d.PartnerID] = r
		}
		amount := d.ActualAmount
		if d.DocType == models.ErpDocSalesReturn {
			// 退货只冲减金额，不计购买频次、不影响最近购买时间
			r.MAmount -= amount
			continue
		}
		r.FCount++
		r.MAmount += amount
		if d.BizDate.After(now.AddDate(0, 0, -r.RDays)) {
			days := int(now.Sub(d.BizDate).Hours() / 24)
			if days < r.RDays {
				r.RDays = days
				r.LastDate = d.BizDate.Format("2006-01-02")
			}
		}
	}
	list := make([]*row, 0, len(agg))
	rs, fs, ms := make([]float64, 0, len(agg)), make([]float64, 0, len(agg)), make([]float64, 0, len(agg))
	for _, r := range agg {
		list = append(list, r)
		rs = append(rs, float64(r.RDays))
		fs = append(fs, float64(r.FCount))
		ms = append(ms, r.MAmount)
	}
	rMed := erpMedian(rs)
	fMed := erpMedian(fs)
	mMed := erpMedian(ms)
	for _, r := range list {
		r.MAmount = round2f(r.MAmount)
		r.RScore = erpHighScore(float64(r.RDays), rMed, true) // R 越小越好
		r.FScore = erpHighScore(float64(r.FCount), fMed, false)
		r.MScore = erpHighScore(r.MAmount, mMed, false)
		r.Segment = erpRFMSegment(r.RScore, r.FScore, r.MScore)
	}
	sort.Slice(list, func(i, j int) bool {
		if list[i].MAmount != list[j].MAmount {
			return list[i].MAmount > list[j].MAmount
		}
		return list[i].CustomerID < list[j].CustomerID
	})
	segCount := map[string]int{}
	for _, r := range list {
		segCount[r.Segment]++
	}
	c.ok(map[string]interface{}{
		"list": list, "median": map[string]float64{"r": rMed, "f": fMed, "m": mMed},
		"segment_counts": segCount,
	})
}

// Dashboard GET /backend/erp/report/dashboard 经营看板
func (c *BackendErpReportController) Dashboard() {
	cl, err := c.claims()
	if c.denied(err) {
		return
	}
	c.ok(erpDashboardCore(erpNewActor(cl), c.GetString("period")))
}

// ---- 汇总报表共用：聚合实现见 erp_report_core.go ----

func absFloat(v float64) float64 {
	if v < 0 {
		return -v
	}
	return v
}

func erpDocPartnerMap(ids []uint64) map[uint64]models.ErpDocument {
	out := map[uint64]models.ErpDocument{}
	if len(ids) == 0 {
		return out
	}
	var docs []models.ErpDocument
	_, _ = models.Orm.QueryTable(new(models.ErpDocument)).
		Filter("id__in", ids).All(&docs, "id", "partner_id", "partner_name", "biz_date")
	for _, d := range docs {
		out[d.ID] = d
	}
	return out
}

func keysOfU64[V any](m map[uint64]V) []uint64 {
	out := make([]uint64, 0, len(m))
	for k := range m {
		out = append(out, k)
	}
	return out
}

func erpMedian(v []float64) float64 {
	if len(v) == 0 {
		return 0
	}
	c := append([]float64{}, v...)
	sort.Float64s(c)
	n := len(c)
	if n%2 == 1 {
		return c[n/2]
	}
	return (c[n/2-1] + c[n/2]) / 2
}

// erpHighScore 1=高于中位数（好），0=低于中位数；reverse=true 表示值越小越好
func erpHighScore(v, med float64, reverse bool) int {
	if reverse {
		if v <= med {
			return 1
		}
		return 0
	}
	if v >= med {
		return 1
	}
	return 0
}

func erpRFMSegment(r, f, m int) string {
	switch {
	case r == 1 && f == 1 && m == 1:
		return "重要价值客户"
	case r == 1 && f == 0 && m == 1:
		return "重要发展客户"
	case r == 0 && f == 1 && m == 1:
		return "重要保持客户"
	case r == 0 && f == 0 && m == 1:
		return "重要挽留客户"
	case r == 1 && f == 1 && m == 0:
		return "一般价值客户"
	case r == 1 && f == 0 && m == 0:
		return "一般发展客户"
	case r == 0 && f == 1 && m == 0:
		return "一般保持客户"
	default:
		return "一般挽留客户"
	}
}

// erpErpPendingTaskCount 待当前用户审批的进销存单据数
func erpErpPendingTaskCount(tid, uid uint64) int64 {
	var rows []models.ApprovalTask
	_, _ = models.Orm.QueryTable(new(models.ApprovalTask)).
		Filter("tid", tid).Filter("approver_id", uid).
		Filter("status", models.ApprovalTaskPending).
		Filter("biz_type__startswith", "erp_").
		Filter("is_deleted", 0).All(&rows, "id")
	return int64(len(rows))
}