// ABOUTME: Parses Kubernetes-style resource notation for CPU and memory.
// ABOUTME: CPU: "500m" = 0.5 cores, "2" = 2 cores.
// ABOUTME: Memory: "1Gi" = 1 GiB, "512Mi" = 512 MiB, "1G" = 1 GB.
package cgroup

import (
	"fmt"
	"strconv"
	"strings"
)

// ParseCPU parses Kubernetes CPU notation to cores.
// Examples: "500m" => 0.5, "2" => 2.0, "100m" => 0.1, "2000m" => 2.0
func ParseCPU(value string) (float64, error) {
	value = strings.TrimSpace(value)
	if value == "" {
		return 0, fmt.Errorf("empty CPU value")
	}

	// Handle millicores suffix
	if strings.HasSuffix(value, "m") {
		millis, err := strconv.ParseFloat(strings.TrimSuffix(value, "m"), 64)
		if err != nil {
			return 0, fmt.Errorf("parsing millicores: %w", err)
		}
		return millis / 1000.0, nil
	}

	// Plain number means cores
	cores, err := strconv.ParseFloat(value, 64)
	if err != nil {
		return 0, fmt.Errorf("parsing cores: %w", err)
	}

	return cores, nil
}

// ParseMemory parses Kubernetes memory notation to bytes.
// Supports:
// - Binary suffixes: Ki, Mi, Gi, Ti (powers of 1024)
// - Decimal suffixes: K, M, G, T (powers of 1000)
// - Plain numbers: bytes
func ParseMemory(value string) (uint64, error) {
	value = strings.TrimSpace(value)
	if value == "" {
		return 0, fmt.Errorf("empty memory value")
	}

	// Binary suffixes (powers of 1024)
	binarySuffixes := map[string]uint64{
		"Ki": 1024,
		"Mi": 1024 * 1024,
		"Gi": 1024 * 1024 * 1024,
		"Ti": 1024 * 1024 * 1024 * 1024,
	}

	// Decimal suffixes (powers of 1000)
	decimalSuffixes := map[string]uint64{
		"K": 1000,
		"M": 1000 * 1000,
		"G": 1000 * 1000 * 1000,
		"T": 1000 * 1000 * 1000 * 1000,
	}

	// Try binary suffixes first (2-char)
	for suffix, multiplier := range binarySuffixes {
		if strings.HasSuffix(value, suffix) {
			numStr := strings.TrimSuffix(value, suffix)
			num, err := strconv.ParseFloat(numStr, 64)
			if err != nil {
				return 0, fmt.Errorf("parsing memory value: %w", err)
			}
			return uint64(num * float64(multiplier)), nil
		}
	}

	// Try decimal suffixes (1-char)
	for suffix, multiplier := range decimalSuffixes {
		if strings.HasSuffix(value, suffix) {
			numStr := strings.TrimSuffix(value, suffix)
			num, err := strconv.ParseFloat(numStr, 64)
			if err != nil {
				return 0, fmt.Errorf("parsing memory value: %w", err)
			}
			return uint64(num * float64(multiplier)), nil
		}
	}

	// Plain number (bytes)
	bytes, err := strconv.ParseUint(value, 10, 64)
	if err != nil {
		return 0, fmt.Errorf("parsing bytes: %w", err)
	}

	return bytes, nil
}