package handler

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

	"aiaa-notification-service/internal/cache"
	"aiaa-notification-service/internal/model"
	"aiaa-notification-service/internal/store"

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

type RuleHandler struct {
	store *store.Store
	cache *cache.Cache
}

func NewRuleHandler(s *store.Store, c *cache.Cache) *RuleHandler {
	return &RuleHandler{store: s, cache: c}
}

type createRuleReq struct {
	Name         string            `json:"name"          binding:"required"`
	SourceName   string            `json:"source_name"   binding:"required"`
	Event        string            `json:"event"         binding:"required"`
	TemplateName string            `json:"template_name" binding:"required"`
	Channels     []string          `json:"channels"`
	Conditions   []model.Condition `json:"conditions,omitempty"`
	Enabled      int               `json:"enabled"`
}

func (h *RuleHandler) Create(c *gin.Context) {
	var req createRuleReq
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	if req.Enabled == 0 {
		req.Enabled = 1
	}

	// Resolve names -> IDs
	src, err := h.store.GetSourceByName(c.Request.Context(), req.SourceName)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "source not found: " + req.SourceName})
		return
	}
	tmpl, err := h.store.GetTemplateByName(c.Request.Context(), req.TemplateName)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "template not found: " + req.TemplateName})
		return
	}
	channelIDs, err := resolveChannelNames(h.store, c, req.Channels)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	var condsJSON *json.RawMessage
	if len(req.Conditions) > 0 {
		data, _ := json.Marshal(req.Conditions)
		raw := json.RawMessage(data)
		condsJSON = &raw
	}

	rule := &model.Rule{
		Name:       req.Name,
		SourceID:   src.ID,
		Event:      req.Event,
		TemplateID: tmpl.ID,
		Conditions: condsJSON,
		Enabled:    req.Enabled,
	}

	if err := h.store.CreateRule(c.Request.Context(), rule, channelIDs); err != nil {
		c.JSON(http.StatusConflict, gin.H{"error": err.Error()})
		return
	}
	rule.Channels = h.loadRuleChannels(c.Request.Context(), rule.ID)
	c.JSON(http.StatusCreated, rule)
}

func (h *RuleHandler) List(c *gin.Context) {
	var page store.PageFilter
	if err := c.ShouldBindQuery(&page); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	page.Normalize()

	rules, total, err := h.store.ListRules(c.Request.Context(), page)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	if err := h.fillRuleChannels(c, rules); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusOK, gin.H{"data": rules, "total": total, "page": page.Page})
}

func (h *RuleHandler) Get(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	rule, err := h.store.GetRule(c.Request.Context(), id)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "rule not found"})
		return
	}
	rule.Channels = h.loadRuleChannels(c.Request.Context(), id)
	c.JSON(http.StatusOK, rule)
}

// loadRuleChannels returns all channels bound to a rule, each with the per-rule
// enabled switch, ordered by rule_channel id.
func (h *RuleHandler) loadRuleChannels(ctx context.Context, ruleID int) []model.RuleChannelItem {
	byRule, err := h.store.ListRuleChannels(ctx, []int{ruleID})
	if err != nil || len(byRule) == 0 {
		return []model.RuleChannelItem{}
	}
	rcs := byRule[ruleID]
	if len(rcs) == 0 {
		return []model.RuleChannelItem{}
	}
	items := make([]model.RuleChannelItem, 0, len(rcs))
	for _, rc := range rcs {
		ch, err := h.store.GetChannel(ctx, rc.ChannelID)
		if err != nil {
			continue
		}
		items = append(items, model.RuleChannelItem{
			ID:      ch.ID,
			Name:    ch.Name,
			Type:    ch.Type,
			Enabled: rc.Enabled,
		})
	}
	return items
}

// fillRuleChannels bulk-loads bound channels for rules and attaches them.
func (h *RuleHandler) fillRuleChannels(ctx context.Context, rules []model.Rule) error {
	if len(rules) == 0 {
		return nil
	}
	ids := make([]int, 0, len(rules))
	for i := range rules {
		ids = append(ids, rules[i].ID)
	}
	byRule, err := h.store.ListRuleChannels(ctx, ids)
	if err != nil {
		return err
	}
	if len(byRule) == 0 {
		return nil
	}
	for i := range rules {
		r := &rules[i]
		rcs := byRule[r.ID]
		if len(rcs) == 0 {
			r.Channels = []model.RuleChannelItem{}
			continue
		}
		items := make([]model.RuleChannelItem, 0, len(rcs))
		for _, rc := range rcs {
			ch, err := h.store.GetChannel(ctx, rc.ChannelID)
			if err != nil {
				continue
			}
			items = append(items, model.RuleChannelItem{
				ID:      ch.ID,
				Name:    ch.Name,
				Type:    ch.Type,
				Enabled: rc.Enabled,
			})
		}
		r.Channels = items
	}
	return nil
}

func (h *RuleHandler) Update(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	var req createRuleReq
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	src, err := h.store.GetSourceByName(c.Request.Context(), req.SourceName)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "source not found"})
		return
	}
	tmpl, err := h.store.GetTemplateByName(c.Request.Context(), req.TemplateName)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "template not found"})
		return
	}
	channelIDs, err := resolveChannelNames(h.store, c, req.Channels)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	var condsJSON *json.RawMessage
	if len(req.Conditions) > 0 {
		data, _ := json.Marshal(req.Conditions)
		raw := json.RawMessage(data)
		condsJSON = &raw
	}

	rule := &model.Rule{
		Name:       req.Name,
		SourceID:   src.ID,
		Event:      req.Event,
		TemplateID: tmpl.ID,
		Conditions: condsJSON,
		Enabled:    req.Enabled,
	}

	if err := h.store.UpdateRule(c.Request.Context(), id, rule, channelIDs); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	// Invalidate cache
	if h.cache != nil {
		_ = h.cache.InvalidateRule(c.Request.Context(), src.ID, req.Event)
		_ = h.cache.InvalidateChannels(c.Request.Context(), id)
	}

	c.JSON(http.StatusOK, gin.H{"ok": true})
}

func (h *RuleHandler) Delete(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	if err := h.store.DeleteRule(c.Request.Context(), id); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusOK, gin.H{"ok": true})
}

func (h *RuleHandler) Enable(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	rule, err := h.store.GetRule(c.Request.Context(), id)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "rule not found"})
		return
	}
	if err := h.store.SetRuleEnabled(c.Request.Context(), id, true); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	if h.cache != nil {
		_ = h.cache.InvalidateRule(c.Request.Context(), rule.SourceID, rule.Event)
	}
	c.JSON(http.StatusOK, gin.H{"ok": true})
}

func (h *RuleHandler) Disable(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	rule, err := h.store.GetRule(c.Request.Context(), id)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "rule not found"})
		return
	}
	if err := h.store.SetRuleEnabled(c.Request.Context(), id, false); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	if h.cache != nil {
		_ = h.cache.InvalidateRule(c.Request.Context(), rule.SourceID, rule.Event)
	}
	c.JSON(http.StatusOK, gin.H{"ok": true})
}

func (h *RuleHandler) EnableChannel(c *gin.Context) {
	ruleID, _ := strconv.Atoi(c.Param("id"))
	channelID, _ := strconv.Atoi(c.Param("channel_id"))
	if err := h.store.SetRuleChannelEnabled(c.Request.Context(), ruleID, channelID, true); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	if h.cache != nil {
		_ = h.cache.InvalidateChannels(c.Request.Context(), ruleID)
	}
	c.JSON(http.StatusOK, gin.H{"ok": true})
}

func (h *RuleHandler) DisableChannel(c *gin.Context) {
	ruleID, _ := strconv.Atoi(c.Param("id"))
	channelID, _ := strconv.Atoi(c.Param("channel_id"))
	if err := h.store.SetRuleChannelEnabled(c.Request.Context(), ruleID, channelID, false); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	if h.cache != nil {
		_ = h.cache.InvalidateChannels(c.Request.Context(), ruleID)
	}
	c.JSON(http.StatusOK, gin.H{"ok": true})
}

func resolveChannelNames(s *store.Store, c *gin.Context, names []string) ([]int, error) {
	var ids []int
	for _, name := range names {
		ch, err := s.GetChannelByName(c.Request.Context(), name)
		if err != nil {
			return nil, err
		}
		ids = append(ids, ch.ID)
	}
	return ids, nil
}