package parser

import (
	"bufio"
	"errors"
	"fmt"
	"os"
	"os/exec"
)

func ParseFile(path string) (Parser, error) {
	if path == "" {
		return Parser{}, errors.New("path cannot be empty")
	}

	if _, err := os.Stat(path); os.IsNotExist(err) {
		return Parser{}, fmt.Errorf("file does not exist: %s", path)
	}

	cmd := exec.Command("tail", "-F", "-n", "10", path)

	stdout, err := cmd.StdoutPipe()
	if err != nil {
		return Parser{}, fmt.Errorf("stdout pipe error: %w", err)
	}

	if err := cmd.Start(); err != nil {
		return Parser{}, fmt.Errorf("failed to start tail parser: %w", err)
	}

	p := Parser{
		parser: bufio.NewScanner(stdout),
		ch:     make(chan string, 100),
		cmd:    cmd,
		file:   &path,
	}

	return p, nil
}