package billingexpr

import (
	"crypto/sha256"
	"fmt"
	"time"

	"github.com/QuantumNous/new-api/common"
)

type RequestInput struct {
	At      *time.Time `json:"at,omitempty"`
	Headers map[string]string
	Body    []byte
	Usage   map[string]any
	// ImageCount is a validated billing quantity, separate from the frozen
	// request's n. Settlement can replace it with the actual returned count.
	ImageCount *int
}

// TokenParams holds all token dimensions passed into an Expr evaluation.
// Fields beyond P and C are optional — when absent they default to 0,
// which means cache-unaware expressions keep working unchanged.
type TokenParams struct {
	P     float64 // prompt tokens (text) — auto-excludes sub-categories priced separately
	C     float64 // completion tokens (text) — auto-excludes sub-categories priced separately
	Len   float64 // total input context length for tier conditions (non-Claude: raw prompt_tokens; Claude: text + cache read + cache creation)
	CR    float64 // cache read (hit) tokens
	CC    float64 // cache creation tokens (5-min TTL for Claude, generic for others)
	CC1h  float64 // cache creation tokens — 1-hour TTL (Claude only)
	Img   float64 // image input tokens
	ImgCR float64 // image cache read tokens, separated only when explicitly priced
	ImgO  float64 // image output tokens
	AI    float64 // audio input tokens
	AO    float64 // audio output tokens
}

// RequestRuleTrace describes one request-dependent multiplier detected at compile time.
type RequestRuleTrace struct {
	Cond       string  `json:"cond"`
	Multiplier float64 `json:"multiplier"`
	Matched    bool    `json:"matched"`
}

type BillingUnit string

const (
	BillingUnitToken   BillingUnit = "token"
	BillingUnitRequest BillingUnit = "request"
)

// TraceResult holds side-channel info captured while an expression runs.
type TraceResult struct {
	ImageCount   *int               `json:"image_count,omitempty"`
	BillingUnit  BillingUnit        `json:"billing_unit"`
	FixedPrice   *float64           `json:"fixed_price,omitempty"`
	MatchedTier  string             `json:"matched_tier"`
	RequestRules []RequestRuleTrace `json:"request_rules,omitempty"`
	Cost         float64            `json:"cost"`
}

// BillingSnapshot captures billing state at pre-consume time. Expression and
// request fields stay frozen; group-dependent fields are refreshed before an
// auto-group retry and settlement. It is fully serializable and contains no
// compiled program pointers.
type BillingSnapshot struct {
	EstimatedImageCount       *int           `json:"estimated_image_count,omitempty"`
	BillingMode               string         `json:"billing_mode"`
	ModelName                 string         `json:"model_name"`
	ExprString                string         `json:"expr_string"`
	ExprHash                  string         `json:"expr_hash"`
	GroupRatio                float64        `json:"group_ratio"`
	EstimatedPromptTokens     int            `json:"estimated_prompt_tokens"`
	EstimatedCompletionTokens int            `json:"estimated_completion_tokens"`
	PreConsumeMultiplier      float64        `json:"pre_consume_multiplier,omitempty"` // Reservation only; zero in older snapshots means 1.
	EstimatedQuotaBeforeGroup float64        `json:"estimated_quota_before_group"`
	EstimatedQuotaAfterGroup  int            `json:"estimated_quota_after_group"`
	EstimatedTier             string         `json:"estimated_tier"`
	EstimatedBillingUnit      BillingUnit    `json:"estimated_billing_unit,omitempty"`
	EstimatedFixedPrice       *float64       `json:"estimated_fixed_price,omitempty"`
	QuotaPerUnit              float64        `json:"quota_per_unit"`
	ExprVersion               int            `json:"expr_version"`
	TaskUsageBilling          bool           `json:"task_usage_billing,omitempty"`
	UsageFacts                map[string]any `json:"usage_facts,omitempty"`
}

// TieredResult holds everything needed after running tiered settlement.
type TieredResult struct {
	// BillingTokens records the actual normalized inputs for successful token
	// billing that explicitly references img_cr. Logs serialize these through
	// the shared injection path, not as additional snapshot state.
	BillingTokens          *TokenParams       `json:"-"`
	ImageCount             *int               `json:"image_count,omitempty"`
	BillingUnit            BillingUnit        `json:"billing_unit"`
	FixedPrice             *float64           `json:"fixed_price,omitempty"`
	ActualQuotaBeforeGroup float64            `json:"actual_quota_before_group"`
	ActualQuotaAfterGroup  int                `json:"actual_quota_after_group"`
	MatchedTier            string             `json:"matched_tier"`
	RequestRules           []RequestRuleTrace `json:"request_rules,omitempty"`
	CrossedTier            bool               `json:"crossed_tier"`
	// Clamp records a single-request saturation event during quota conversion so the
	// caller can surface it on the consume log for admin auditing. Nil when no
	// clamping occurred. Not serialized: the marker is attached separately via
	// the shared quota-saturation audit path.
	Clamp *common.QuotaClamp `json:"-"`
}

// ExprHashString returns the SHA-256 hex digest of an expression string.
func ExprHashString(expr string) string {
	h := sha256.Sum256([]byte(expr))
	return fmt.Sprintf("%x", h)
}