/*
Copyright © 2022 Thomas von Dein

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/

package lib

import (
	"errors"
	"github.com/tlinden/tablizer/cfg"
	"io"
	"os"
)

func ProcessFiles(c *cfg.Config, args []string) error {
	fds, pattern, err := determineIO(c, args)

	if err != nil {
		return err
	}

	if err := c.PreparePattern(pattern); err != nil {
		return err
	}

	for _, fd := range fds {
		data, err := Parse(*c, fd)
		if err != nil {
			return err
		}

		err = PrepareColumns(c, &data)
		if err != nil {
			return err
		}

		printData(os.Stdout, *c, &data)
	}

	return nil
}

func determineIO(c *cfg.Config, args []string) ([]io.Reader, string, error) {
	var pattern string
	var fds []io.Reader
	var haveio bool

	stat, _ := os.Stdin.Stat()
	if (stat.Mode() & os.ModeCharDevice) == 0 {
		// we're reading from STDIN, which takes precedence over file args
		fds = append(fds, os.Stdin)
		if len(args) > 0 {
			// ignore any args > 1
			pattern = args[0]
			c.Pattern = args[0] // used for colorization by printData()
		}
		haveio = true
	} else {
		if len(args) > 0 {
			// threre were args left, take a look
			if args[0] == "-" {
				// in traditional unix programs a dash denotes STDIN (forced)
				fds = append(fds, os.Stdin)
				haveio = true
			} else {
				if _, err := os.Stat(args[0]); err != nil {
					// first  one is  not a  file, consider  it as  regexp and
					// shift arg list
					pattern = args[0]
					c.Pattern = args[0] // used for colorization by printData()
					args = args[1:]
				}

				if len(args) > 0 {
					// consider any other args as files
					for _, file := range args {

						fd, err := os.OpenFile(file, os.O_RDONLY, 0755)

						if err != nil {
							return nil, "", err
						}

						fds = append(fds, fd)
						haveio = true
					}
				}
			}
		}
	}

	if !haveio {
		return nil, "", errors.New("No file specified and nothing to read on stdin!")
	}

	return fds, pattern, nil
}