package llm

import (
	"sync"
	"time"
)

type CallRecord struct {
	ID           string    `json:"id"`
	Time         time.Time `json:"time"`
	Model        string    `json:"model"`
	Purpose      string    `json:"purpose"`
	PromptTokens int       `json:"prompt_tokens"`
	CompTokens   int       `json:"completion_tokens"`
	DurationMs   int64     `json:"duration_ms"`
	Success      bool      `json:"success"`
	Error        string    `json:"error,omitempty"`
}

type Logger struct {
	mu      sync.RWMutex
	records []CallRecord
	max     int
	index   int
	total   int64
}

func NewLogger(max int) *Logger { return &Logger{records: make([]CallRecord, max), max: max} }

func (l *Logger) Record(r CallRecord) {
	l.mu.Lock()
	defer l.mu.Unlock()
	r.ID = time.Now().Format("150405") + "-" + r.Purpose
	l.records[l.index%l.max] = r
	l.index++
	l.total++
}

func (l *Logger) Recent(n int) []CallRecord {
	l.mu.RLock()
	defer l.mu.RUnlock()
	if n > l.max { n = l.max }
	count := l.index
	if count > l.max { count = l.max }
	if n > count { n = count }
	result := make([]CallRecord, n)
	for i := 0; i < n; i++ {
		idx := (l.index - 1 - i + l.max) % l.max
		if idx < l.max { result[n-1-i] = l.records[idx] }
	}
	return result
}

func (l *Logger) RecentMaps(n int) []map[string]any {
	records := l.Recent(n)
	result := make([]map[string]any, len(records))
	for i, r := range records {
		result[i] = map[string]any{
			"id": r.ID, "time": r.Time.Format(time.RFC3339), "model": r.Model,
			"purpose": r.Purpose, "prompt_tokens": r.PromptTokens, "completion_tokens": r.CompTokens,
			"duration_ms": r.DurationMs, "success": r.Success, "error": r.Error,
		}
	}
	return result
}

func (l *Logger) Stats() map[string]any {
	l.mu.RLock()
	defer l.mu.RUnlock()
	var calls, succ int64
	var dur, tok int64
	count := l.index
	if count > l.max { count = l.max }
	for i := 0; i < count; i++ {
		r := l.records[(l.index-1-i+l.max)%l.max]
		calls++
		if r.Success { succ++ }
		dur += r.DurationMs
		tok += int64(r.PromptTokens + r.CompTokens)
	}
	avg := 0
	if calls > 0 { avg = int(dur / calls) }
	return map[string]any{"total_calls": calls, "success_calls": succ, "avg_duration_ms": avg, "total_tokens": tok}
}