package service

import (
	"fmt"
	"math/rand"
	"regexp"
	"sort"
	"strconv"
	"strings"

	"gcy_hpc_server/internal/model"
)

var paramNameRegex = regexp.MustCompile(`^[A-Za-z_][A-Za-z0-9_]*$`)

// ValidateParams checks that all required parameters are present and values match their types.
// Parameters not in the schema are silently ignored.
func ValidateParams(params []model.ParameterSchema, values map[string]string) error {
	var errs []string

	for _, p := range params {
		if !paramNameRegex.MatchString(p.Name) {
			errs = append(errs, fmt.Sprintf("invalid parameter name %q: must match ^[A-Za-z_][A-Za-z0-9_]*$", p.Name))
			continue
		}

		val, ok := values[p.Name]

		if p.Required && !ok {
			errs = append(errs, fmt.Sprintf("required parameter %q is missing", p.Name))
			continue
		}

		if !ok {
			continue
		}

		switch p.Type {
		case model.ParamTypeInteger:
			if _, err := strconv.Atoi(val); err != nil {
				errs = append(errs, fmt.Sprintf("parameter %q must be an integer, got %q", p.Name, val))
			}
		case model.ParamTypeBoolean:
			if val != "true" && val != "false" && val != "1" && val != "0" {
				errs = append(errs, fmt.Sprintf("parameter %q must be a boolean (true/false/1/0), got %q", p.Name, val))
			}
		case model.ParamTypeEnum:
			if len(p.Options) > 0 {
				found := false
				for _, opt := range p.Options {
					if val == opt {
						found = true
						break
					}
				}
				if !found {
					errs = append(errs, fmt.Sprintf("parameter %q must be one of %v, got %q", p.Name, p.Options, val))
				}
			}
		case model.ParamTypeFile, model.ParamTypeDirectory:
		case model.ParamTypeString:
		}
	}

	if len(errs) > 0 {
		return fmt.Errorf("parameter validation failed: %s", strings.Join(errs, "; "))
	}
	return nil
}

// RenderScript replaces $PARAM tokens in the template with user-provided values.
// Only tokens defined in the schema are replaced. Replacement is done longest-name-first
// to avoid partial matches (e.g., $JOB_NAME before $JOB).
// All values are shell-escaped using single-quote wrapping.
func RenderScript(template string, params []model.ParameterSchema, values map[string]string) string {
	sorted := make([]model.ParameterSchema, len(params))
	copy(sorted, params)
	sort.Slice(sorted, func(i, j int) bool {
		return len(sorted[i].Name) > len(sorted[j].Name)
	})

	result := template
	for _, p := range sorted {
		val, ok := values[p.Name]
		if !ok {
			if p.Default != "" {
				val = p.Default
			} else {
				continue
			}
		}
		escaped := "'" + strings.ReplaceAll(val, "'", "'\\''") + "'"
		result = strings.ReplaceAll(result, "$"+p.Name, escaped)
	}
	return result
}

// SanitizeDirName sanitizes a directory name.
func SanitizeDirName(name string) string {
	replacer := strings.NewReplacer(" ", "_", "/", "_", "\\", "_", ":", "_", "*", "_", "?", "_", "\"", "_", "<", "_", ">", "_", "|", "_")
	return replacer.Replace(name)
}

// RandomSuffix generates a random suffix of length n.
func RandomSuffix(n int) string {
	const charset = "abcdefghijklmnopqrstuvwxyz0123456789"
	b := make([]byte, n)
	for i := range b {
		b[i] = charset[rand.Intn(len(charset))]
	}
	return string(b)
}