package task

import (
	"fmt"
	"os"
	"time"

	"github.com/google/uuid"
	"gopkg.in/yaml.v3"
)

// ParseFile reads a YAML file and returns tasks. Supports both single-task
// and batch (tasks: [...]) formats.
func ParseFile(path string) ([]Task, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("reading task file: %w", err)
	}
	return Parse(data)
}

// Parse parses YAML bytes into tasks.
func Parse(data []byte) ([]Task, error) {
	// Try batch format first.
	var batch BatchFile
	if err := yaml.Unmarshal(data, &batch); err == nil && len(batch.Tasks) > 0 {
		return initTasks(batch.Tasks), nil
	}

	// Try single task.
	var t Task
	if err := yaml.Unmarshal(data, &t); err != nil {
		return nil, fmt.Errorf("parsing task YAML: %w", err)
	}
	if t.Name == "" {
		return nil, fmt.Errorf("task must have a name")
	}
	return initTasks([]Task{t}), nil
}

func initTasks(tasks []Task) []Task {
	now := time.Now()
	for i := range tasks {
		if tasks[i].ID == "" {
			tasks[i].ID = uuid.New().String()
		}
		if tasks[i].Priority == "" {
			tasks[i].Priority = PriorityNormal
		}
		if tasks[i].Retry.MaxAttempts == 0 {
			tasks[i].Retry.MaxAttempts = 1
		}
		if tasks[i].Retry.Backoff == "" {
			tasks[i].Retry.Backoff = "exponential"
		}
		tasks[i].State = StatePending
		tasks[i].CreatedAt = now
		tasks[i].UpdatedAt = now
	}
	return tasks
}