// Package debugbundle owns explicitly requested per-run debug bundles.
package debugbundle

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"time"
)

const maxCreateAttempts = 16

var utcNow = func() time.Time { return time.Now().UTC() }

type Bundle struct {
	path, summaryRoot, traceRoot string
	createdAt                    time.Time
}

func Allocate(parent string) (*Bundle, error) {
	parent = strings.TrimSpace(parent)
	if parent == "" {
		return nil, fmt.Errorf("debug parent must not be empty")
	}
	if err := os.MkdirAll(parent, 0o700); err != nil {
		return nil, fmt.Errorf("create debug parent %q: %w", parent, err)
	}
	var last string
	for attempt := 0; attempt < maxCreateAttempts; attempt++ {
		createdAt := utcNow()
		runID := fmt.Sprintf("run-%d", createdAt.UnixNano())
		path := filepath.Join(parent, runID)
		last = path
		if err := os.Mkdir(path, 0o700); err != nil {
			if os.IsExist(err) {
				continue
			}
			return nil, fmt.Errorf("create debug bundle %q: %w", path, err)
		}
		summary, trace := filepath.Join(path, "summary"), filepath.Join(path, "trace")
		if err := os.Mkdir(summary, 0o700); err != nil {
			_ = os.Remove(path)
			return nil, fmt.Errorf("create debug summary %q: %w", summary, err)
		}
		if err := os.Mkdir(trace, 0o700); err != nil {
			_ = os.RemoveAll(path)
			return nil, fmt.Errorf("create debug trace %q: %w", trace, err)
		}
		return &Bundle{path: path, summaryRoot: summary, traceRoot: trace, createdAt: createdAt}, nil
	}
	return nil, fmt.Errorf("create debug bundle %q: exhausted unique run ID attempts", last)
}
func (b *Bundle) Path() string {
	if b == nil {
		return ""
	}
	return b.path
}
func (b *Bundle) SummaryRoot() string {
	if b == nil {
		return ""
	}
	return b.summaryRoot
}
func (b *Bundle) TraceRoot() string {
	if b == nil {
		return ""
	}
	return b.traceRoot
}
func (b *Bundle) RunID() string {
	if b == nil {
		return ""
	}
	return filepath.Base(b.path)
}
func (b *Bundle) CreatedAt() time.Time {
	if b == nil {
		return time.Time{}
	}
	return b.createdAt
}
func (b *Bundle) Summary() *SummaryWriter {
	if b == nil {
		return nil
	}
	return &SummaryWriter{root: b.summaryRoot, runID: b.RunID(), createdAt: b.createdAt}
}