package runner

import (
	"context"
	"math"
	"strings"

	"github.com/easyai/easyai-ai-gateway/apps/api/internal/auth"
	"github.com/easyai/easyai-ai-gateway/apps/api/internal/clients"
	"github.com/easyai/easyai-ai-gateway/apps/api/internal/store"
)

type EstimateResult struct {
	Items    []any  `json:"items"`
	Resolver string `json:"resolver"`
}

func (s *Service) Estimate(ctx context.Context, kind string, model string, body map[string]any, user *auth.User) (EstimateResult, error) {
	candidates, err := s.store.ListModelCandidates(ctx, model, modelTypeFromKind(kind))
	if err != nil {
		return EstimateResult{}, err
	}
	candidate := candidates[0]
	usage := clients.Usage{InputTokens: estimateRequestTokens(body), OutputTokens: int(floatFromAny(body["max_tokens"]))}
	if usage.OutputTokens == 0 {
		usage.OutputTokens = 64
	}
	usage.TotalTokens = usage.InputTokens + usage.OutputTokens
	response := clients.Response{Usage: usage, Result: map[string]any{"usage": map[string]any{
		"prompt_tokens":     usage.InputTokens,
		"completion_tokens": usage.OutputTokens,
		"total_tokens":      usage.TotalTokens,
	}}}
	return EstimateResult{
		Items:    s.billings(ctx, user, kind, body, candidate, response, true),
		Resolver: "effective-pricing-v1",
	}, nil
}

func (s *Service) billings(ctx context.Context, user *auth.User, kind string, body map[string]any, candidate store.RuntimeModelCandidate, response clients.Response, simulated bool) []any {
	config := effectiveBillingConfig(candidate)
	discount := effectiveDiscount(ctx, s.store, user, candidate)
	if modelTypeFromKind(kind) == "chat" {
		inputTokens := response.Usage.InputTokens
		outputTokens := response.Usage.OutputTokens
		if inputTokens == 0 && outputTokens == 0 {
			inputTokens = estimateRequestTokens(body)
			outputTokens = 1
		}
		inputAmount := roundPrice(float64(inputTokens) / 1000 * price(config, "textInputPer1k") * discount)
		outputAmount := roundPrice(float64(outputTokens) / 1000 * price(config, "textOutputPer1k") * discount)
		return []any{
			billingLine(candidate, "text_input", "1k_tokens", inputTokens, inputAmount, discount, simulated),
			billingLine(candidate, "text_output", "1k_tokens", outputTokens, outputAmount, discount, simulated),
		}
	}
	count := int(floatFromAny(body["n"]))
	if count <= 0 {
		count = 1
	}
	resource := "image"
	baseKey := "imageBase"
	if kind == "images.edits" {
		resource = "image_edit"
		baseKey = "editBase"
	}
	amount := float64(count) * price(config, baseKey) * weighted(config, "qualityWeights", stringFromMap(body, "quality")) * weighted(config, "sizeWeights", stringFromMap(body, "size")) * discount
	return []any{billingLine(candidate, resource, "image", count, roundPrice(amount), discount, simulated)}
}

func effectiveBillingConfig(candidate store.RuntimeModelCandidate) map[string]any {
	base := candidate.BaseBillingConfig
	if len(candidate.BillingConfig) > 0 {
		base = candidate.BillingConfig
	}
	if len(candidate.BillingConfigOverride) > 0 {
		base = mergeMap(base, candidate.BillingConfigOverride)
	}
	return base
}

func effectiveDiscount(ctx context.Context, db *store.Store, user *auth.User, candidate store.RuntimeModelCandidate) float64 {
	discount := candidate.DefaultDiscountFactor
	if candidate.DiscountFactor > 0 {
		discount = candidate.DiscountFactor
	}
	if discount <= 0 {
		discount = 1
	}
	if group, err := db.ResolveUserGroupPolicy(ctx, user); err == nil {
		groupDiscount := floatFromAny(group.BillingDiscountPolicy["discountFactor"])
		if groupDiscount > 0 {
			discount *= groupDiscount
		}
	}
	return discount
}

func billingLine(candidate store.RuntimeModelCandidate, resourceType string, unit string, quantity any, amount float64, discount float64, simulated bool) map[string]any {
	return map[string]any{
		"model":           candidate.ModelName,
		"modelAlias":      candidate.ModelAlias,
		"provider":        candidate.Provider,
		"platformId":      candidate.PlatformID,
		"platformModelId": candidate.PlatformModelID,
		"resourceType":    resourceType,
		"unit":            unit,
		"quantity":        quantity,
		"amount":          amount,
		"currency":        "resource",
		"discountFactor":  discount,
		"simulated":       simulated,
	}
}

func price(config map[string]any, key string) float64 {
	value := floatFromAny(config[key])
	if value > 0 {
		return value
	}
	return 0
}

func weighted(config map[string]any, key string, name string) float64 {
	if strings.TrimSpace(name) == "" {
		return 1
	}
	weights, _ := config[key].(map[string]any)
	if value := floatFromAny(weights[name]); value > 0 {
		return value
	}
	return 1
}

func roundPrice(value float64) float64 {
	return math.Round(value*1000000) / 1000000
}

func mergeMap(base map[string]any, override map[string]any) map[string]any {
	out := map[string]any{}
	for key, value := range base {
		out[key] = value
	}
	for key, value := range override {
		out[key] = value
	}
	return out
}