package service

import (
	"context"
	"encoding/json"
	"fmt"
	"math/rand"
	"os"
	"path/filepath"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"time"

	"gcy_hpc_server/internal/model"
	"gcy_hpc_server/internal/store"

	"go.uber.org/zap"
)

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

// ApplicationService handles parameter validation, script rendering, and job
// submission for parameterized HPC applications.
type ApplicationService struct {
	store       *store.ApplicationStore
	jobSvc      *JobService
	workDirBase string
	logger      *zap.Logger
}

func NewApplicationService(store *store.ApplicationStore, jobSvc *JobService, workDirBase string, logger *zap.Logger) *ApplicationService {
	return &ApplicationService{store: store, jobSvc: jobSvc, workDirBase: workDirBase, logger: logger}
}

// ValidateParams checks that all required parameters are present and values match their types.
// Parameters not in the schema are silently ignored.
func (s *ApplicationService) 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 (s *ApplicationService) 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
}

// ListApplications delegates to the store.
func (s *ApplicationService) ListApplications(ctx context.Context, page, pageSize int) ([]model.Application, int, error) {
	return s.store.List(ctx, page, pageSize)
}

// CreateApplication delegates to the store.
func (s *ApplicationService) CreateApplication(ctx context.Context, req *model.CreateApplicationRequest) (int64, error) {
	return s.store.Create(ctx, req)
}

// GetApplication delegates to the store.
func (s *ApplicationService) GetApplication(ctx context.Context, id int64) (*model.Application, error) {
	return s.store.GetByID(ctx, id)
}

// UpdateApplication delegates to the store.
func (s *ApplicationService) UpdateApplication(ctx context.Context, id int64, req *model.UpdateApplicationRequest) error {
	return s.store.Update(ctx, id, req)
}

// DeleteApplication delegates to the store.
func (s *ApplicationService) DeleteApplication(ctx context.Context, id int64) error {
	return s.store.Delete(ctx, id)
}

// SubmitFromApplication orchestrates the full submission flow:
// 1. Fetch application by ID
// 2. Parse parameters schema
// 3. Validate parameter values
// 4. Render script template
// 5. Submit job via JobService
func (s *ApplicationService) SubmitFromApplication(ctx context.Context, applicationID int64, values map[string]string) (*model.JobResponse, error) {
	app, err := s.store.GetByID(ctx, applicationID)
	if err != nil {
		return nil, fmt.Errorf("get application: %w", err)
	}
	if app == nil {
		return nil, fmt.Errorf("application %d not found", applicationID)
	}

	var params []model.ParameterSchema
	if len(app.Parameters) > 0 {
		if err := json.Unmarshal(app.Parameters, &params); err != nil {
			return nil, fmt.Errorf("parse parameters: %w", err)
		}
	}

	if err := s.ValidateParams(params, values); err != nil {
		return nil, err
	}

	rendered := s.RenderScript(app.ScriptTemplate, params, values)

	workDir := ""
	if s.workDirBase != "" {
		safeName := sanitizeDirName(app.Name)
		subDir := time.Now().Format("20060102_150405") + "_" + randomSuffix(4)
		workDir = filepath.Join(s.workDirBase, safeName, subDir)
		if err := os.MkdirAll(workDir, 0777); err != nil {
			return nil, fmt.Errorf("create work directory %s: %w", workDir, err)
		}
		// 绕过 umask，确保整条路径都有写权限
		for dir := workDir; dir != s.workDirBase; dir = filepath.Dir(dir) {
			os.Chmod(dir, 0777)
		}
		os.Chmod(s.workDirBase, 0777)
	}

	req := &model.SubmitJobRequest{Script: rendered, WorkDir: workDir}
	return s.jobSvc.SubmitJob(ctx, req)
}

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

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)
}