package mcp

import (
	"context"
	"encoding/json"
	"log/slog"
	"time"
)

// logToolCall emits one structured record per tools/call (hyperguild#144,
// OWASP MCP08): who called which tool, against which wing/hall, and how it
// ended. Brain content is never copied into the record — only its size — so
// the audit trail does not become a second, unscrubbed copy of the brain.
func logToolCall(ctx context.Context, name string, args json.RawMessage, start time.Time, err error) {
	origin, principal := provenanceFrom(ctx)
	attrs := []any{
		"tool", name,
		"principal", principal,
		"origin", origin,
		"duration_ms", time.Since(start).Milliseconds(),
	}
	var a struct {
		Wing    string `json:"wing"`
		Hall    string `json:"hall"`
		Content string `json:"content"`
	}
	if json.Unmarshal(args, &a) == nil {
		if a.Wing != "" {
			attrs = append(attrs, "wing", a.Wing)
		}
		if a.Hall != "" {
			attrs = append(attrs, "hall", a.Hall)
		}
		if a.Content != "" {
			attrs = append(attrs, "content_bytes", len(a.Content))
		}
	}
	// The outcome is a class, never the error text: handler errors echo
	// argument values (a rejected half_life, a requested path), which would
	// make the audit line a copy of what the caller sent (PR #147 review E6).
	// The caller already received the full error in the tool response.
	outcome := "ok"
	if err != nil {
		outcome = "error"
	}
	attrs = append(attrs, "outcome", outcome)
	slog.InfoContext(ctx, "mcp tool call", attrs...)
}