package supervisor

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

// WriteReport generates a markdown report for a completed task and writes it
// to the reports directory. Returns the path to the generated report file.
func WriteReport(task Task, run RunResult, verify VerifyResult, reportsDir string) (string, error) {
	if err := os.MkdirAll(reportsDir, 0755); err != nil {
		return "", fmt.Errorf("create reports dir: %w", err)
	}

	filename := fmt.Sprintf("%s-report.md", task.ID)
	path := filepath.Join(reportsDir, filename)

	content := buildReport(task, run, verify)

	if err := os.WriteFile(path, []byte(content), 0644); err != nil {
		return "", fmt.Errorf("write report: %w", err)
	}

	return path, nil
}

// buildReport generates the markdown content for a task report.
func buildReport(task Task, run RunResult, verify VerifyResult) string {
	var b strings.Builder

	// Header
	fmt.Fprintf(&b, "# %s: %s\n\n", task.ID, task.Title)

	// Metadata
	fmt.Fprintf(&b, "**Datum:** %s\n", run.StartedAt.Format("2006-01-02 15:04"))
	fmt.Fprintf(&b, "**Trajanje:** %s\n", formatDuration(run.Duration))

	if verify.AllPassed {
		b.WriteString("**Status:** ✅ Završen\n")
	} else {
		b.WriteString("**Status:** ❌ Neuspešan\n")
	}

	// Verification
	b.WriteString("\n## Verifikacija\n")
	for _, c := range []CheckResult{verify.Build, verify.Vet, verify.Test} {
		icon := "✅"
		if c.Status == "fail" {
			icon = "❌"
		}
		line := fmt.Sprintf("- %s %s (%s)", icon, c.Name, c.Duration.Round(time.Millisecond))
		if c.Name == "test" && c.TestCount > 0 {
			line = fmt.Sprintf("- %s %s (%d testova, %s)", icon, c.Name, c.TestCount, c.Duration.Round(time.Millisecond))
		}
		b.WriteString(line + "\n")
	}

	// Agent output
	b.WriteString("\n## Agent output\n")
	b.WriteString(truncateOutput(run.Output, 50))
	b.WriteString("\n")

	return b.String()
}

// formatDuration formats a duration as "Xm Ys" or "Xs" for short durations.
func formatDuration(d time.Duration) string {
	d = d.Round(time.Second)
	minutes := int(d.Minutes())
	seconds := int(d.Seconds()) % 60

	if minutes > 0 {
		return fmt.Sprintf("%dm %ds", minutes, seconds)
	}
	return fmt.Sprintf("%ds", seconds)
}

// truncateOutput keeps only the last maxLines lines of output.
func truncateOutput(output string, maxLines int) string {
	if output == "" {
		return "(nema outputa)\n"
	}

	lines := strings.Split(strings.TrimRight(output, "\n"), "\n")
	if len(lines) <= maxLines {
		return strings.Join(lines, "\n") + "\n"
	}

	truncated := lines[len(lines)-maxLines:]
	return fmt.Sprintf("... (skraćeno, prikazano poslednjih %d od %d linija)\n%s\n",
		maxLines, len(lines), strings.Join(truncated, "\n"))
}