package task_logs

/* ***** BEGIN GPL LICENSE BLOCK *****
 *
 * Original Code Copyright (C) 2022 Blender Foundation.
 *
 * This file is part of Flamenco.
 *
 * Flamenco 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.
 *
 * Flamenco 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
 * Flamenco.  If not, see <https://www.gnu.org/licenses/>.
 *
 * ***** END GPL LICENSE BLOCK ***** */

import (
	"fmt"
	"os"
	"path"
	"path/filepath"

	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"
)

// Storage can write data to task logs, rotate logs, etc.
type Storage struct {
	BasePath string // Directory where task logs are stored.
}

// NewStorage creates a new log storage rooted at `basePath`.
func NewStorage(basePath string) *Storage {
	if !filepath.IsAbs(basePath) {
		absPath, err := filepath.Abs(basePath)
		if err != nil {
			log.Panic().Err(err).Str("path", basePath).Msg("cannot resolve relative path to task logs")
		}
		basePath = absPath
	}

	log.Info().
		Str("path", basePath).
		Msg("task logs")

	return &Storage{
		BasePath: basePath,
	}
}

func (s *Storage) Write(logger zerolog.Logger, jobID, taskID string, logText string) error {
	// Shortcut to avoid creating an empty log file. It also solves an
	// index out of bounds error further down when we check the last character.
	if logText == "" {
		return nil
	}

	filepath := s.filepath(jobID, taskID)
	logger = logger.With().Str("filepath", filepath).Logger()

	if err := os.MkdirAll(path.Dir(filepath), 0755); err != nil {
		logger.Error().Err(err).Msg("unable to create directory for log file")
		return fmt.Errorf("error creating directory: %w", err)
	}

	file, err := os.OpenFile(filepath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
	if err != nil {
		logger.Error().Err(err).Msg("unable to open log file for append/create/write")
		return fmt.Errorf("unable to open log file for append/create/write: %w", err)
	}

	if n, err := file.WriteString(logText); n < len(logText) || err != nil {
		logger.Error().
			Int("written", n).
			Int("totalLength", len(logText)).
			Err(err).
			Msg("could only write partial log file")
		file.Close()
		return fmt.Errorf("could only write partial log file: %w", err)
	}

	if logText[len(logText)-1] != '\n' {
		if n, err := file.WriteString("\n"); n < 1 || err != nil {
			logger.Error().Err(err).Msg("could not append line end")
			file.Close()
			return err
		}
	}

	if err := file.Close(); err != nil {
		logger.Error().Err(err).Msg("error closing log file")
		return err
	}
	return nil
}

// RotateFile rotates the task's log file, ignoring (but logging) any errors that occur.
func (s *Storage) RotateFile(logger zerolog.Logger, jobID, taskID string) {
	logpath := s.filepath(jobID, taskID)
	logger = logger.With().Str("logpath", logpath).Logger()

	err := rotateLogFile(logger, logpath)
	if err != nil {
		// rotateLogFile() has already logged something, so we can ignore `err`.
		logger.Trace().Err(err).Msg("ignoring error from log rotation")
	}
}

// filepath returns the file path suitable to write a log file.
func (s *Storage) filepath(jobID, taskID string) string {
	var dirpath string
	if jobID == "" {
		dirpath = path.Join(s.BasePath, "jobless")
	} else {
		dirpath = path.Join(s.BasePath, "job-"+jobID[:4], jobID)
	}
	filename := fmt.Sprintf("task-%v.txt", taskID)
	return path.Join(dirpath, filename)
}