package routing

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"time"
)

// LogEntry describes a single routing decision to log via the brain MCP.
type LogEntry struct {
	SessionID   string
	Skill       string // the original skill the call routed (e.g., "review")
	Decision    string // "local" or "claude" or "claude_fallback"
	Message     string // free-form, e.g. "model=qwen35, pass_rate=0.94"
	ProjectRoot string
	DurationMs  int64
	Failed      bool // true → final_status: "fail"; false → "skip"
}

// Logger posts session_log entries to a brain MCP at BrainURL + /mcp.
type Logger struct {
	BrainURL string
	HTTP     *http.Client
}

// NewLogger creates a Logger with a 2-second HTTP timeout.
func NewLogger(brainURL string) *Logger {
	return &Logger{
		BrainURL: brainURL,
		HTTP:     &http.Client{Timeout: 2 * time.Second},
	}
}

// LogDecision posts a session_log MCP call. Errors are returned but the caller
// MUST NOT block real work on them — logging is best-effort.
func (l *Logger) LogDecision(ctx context.Context, e LogEntry) error {
	status := "skip"
	if e.Failed {
		status = "fail"
	}
	payload := map[string]any{
		"jsonrpc": "2.0",
		"id":      1,
		"method":  "tools/call",
		"params": map[string]any{
			"name": "session_log",
			"arguments": map[string]any{
				"session_id":   e.SessionID,
				"skill":        "_routing",
				"phase":        "decide",
				"final_status": status,
				"message":      fmt.Sprintf("%s: %s — %s", e.Skill, e.Decision, e.Message),
				"duration_ms":  e.DurationMs,
				"project_root": e.ProjectRoot,
			},
		},
	}
	body, err := json.Marshal(payload)
	if err != nil {
		return fmt.Errorf("log: marshal: %w", err)
	}
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, l.BrainURL+"/mcp", bytes.NewReader(body))
	if err != nil {
		return fmt.Errorf("log: build request: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")
	resp, err := l.HTTP.Do(req)
	if err != nil {
		return fmt.Errorf("log: request: %w", err)
	}
	defer func() { _ = resp.Body.Close() }()
	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("log: server returned status %d", resp.StatusCode)
	}
	return nil
}