package tools

import (
	"context"
	"fmt"
	"strconv"
	"strings"

	"github.com/modelcontextprotocol/go-sdk/mcp"
)

// registerDiskTools добавляет точные инструменты диска: по конкретному пути
// (безпотерьный ответ "сколько места на X") и по всем точкам монтирования.
// Отличается от ssh__usage, который исторически отдавал только корень /.
func registerDiskTools(s *mcp.Server) {
	s.AddTool(&mcp.Tool{
		Name:        "disk_usage",
		Description: "Get free/used space for the filesystem that contains the given path (df equivalent). Resolves the MOUND, not just root: returns the mount point, device, size, used, available and use% for the volume holding <path>. Use for 'how much space/free on <path>'.",
		InputSchema: schema(map[string]any{
			"path":   strProps("Absolute path; reports the filesystem that contains it", true),
			"target": strProps("Connection alias (default: primary)", false),
		}, []string{"path"}),
	}, diskUsageHandler)

	s.AddTool(&mcp.Tool{
		Name:        "disk_usage_all",
		Description: "Get free/used space for ALL mounted filesystems (df over every mount point) with a marker on partitions that are >=80% used. Use for an overview of disk pressure.",
		InputSchema: schema(map[string]any{
			"target": strProps("Connection alias (default: primary)", false),
		}, nil),
	}, diskUsageAllHandler)
}

func diskUsageHandler(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
	m := manager()
	if m == nil {
		return errorResult("no SSH manager initialized"), nil
	}
	args := requestArgs(req)
	path, err := requireString(args, "path")
	if err != nil {
		return errorResult(err.Error()), nil
	}
	target := getString(args, "target", "primary")

	// df -hP <path> reports the FS containing <path> (mount point), not just
	// root. shellQuote guards the path; if the path doesn't exist yet (e.g., a
	// not-yet-mounted volume) we degrade to the full mount list rather than fail.
	cmd := diskUsageCmd(path)
	output, err := m.Execute(ctx, cmd, target)
	if err != nil {
		return errorResult(err.Error()), nil
	}
	return textResult(output), nil
}

func diskUsageAllHandler(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
	m := manager()
	if m == nil {
		return errorResult("no SSH manager initialized"), nil
	}
	target := getString(requestArgs(req), "target", "primary")
	output, err := m.Execute(ctx, "df -hP 2>/dev/null", target)
	if err != nil {
		return errorResult(err.Error()), nil
	}
	return textResult(highlightHighUsage(output)), nil
}

// diskUsageCmd собирает команду "место на томе, содержащем path".
func diskUsageCmd(path string) string {
	return fmt.Sprintf("df -hP %s 2>/dev/null || df -hP 2>/dev/null", shellQuote(path))
}

// highlightHighUsage помечает строки df с заполненностью >=80% (иначе
// "почти полный" раздел выпадал у ssh__diagnose_system из-за фильтра >90%).
// Парсим в Go, а не awk: тестируемо и не зависит от полей awk.
func highlightHighUsage(dfOut string) string {
	if strings.TrimSpace(dfOut) == "" {
		return dfOut
	}
	var b strings.Builder
	for _, line := range strings.Split(dfOut, "\n") {
		b.WriteString(line)
		fields := strings.Fields(line)
		// POSIX df -hP: колонка 5 (индекс 4) — "Use%" вроде "84%".
		if len(fields) >= 5 {
			if pct, err := strconv.Atoi(strings.TrimSuffix(fields[4], "%")); err == nil && pct >= 80 {
				b.WriteString("  << USE>=80%")
			}
		}
		b.WriteByte('\n')
	}
	return strings.TrimRight(b.String(), "\n")
}