/*
  Pominal
  Copyright (C) 2020  Daniel Anglin

  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 main

import (
	"encoding/json"
	"os"
)

// Pominal config is a type used to configure Pominal
type PominalConfig struct {
	MaxWorkSessions int      `json:"max-work-sessions"`
	Sessions        Sessions `json:"sessions"`
}

type Sessions struct {
	Work       SessionConfig `json:"work"`
	ShortBreak SessionConfig `json:"short-break"`
	LongBreak  SessionConfig `json:"long-break"`
}

type SessionConfig struct {
	Duration            string `json:"duration"`
	NotificationMessage string `json:"notification-message"`
}

// newPominalConfig creates a new value of type config which will configure
// Pominal based on the configuration set in the configuration file
// and the command-line flags.
func newPominalConfig(file string, workTime, shortBreakTime, longBreakTime string, maxWorkSessions int) (PominalConfig, error) {
	c, err := configureFromFile(file)
	if err != nil {
		return PominalConfig{}, err
	}

	c = configureFlagOverrides(c, workTime, shortBreakTime, longBreakTime, maxWorkSessions)

	return c, nil
}

// configureFromFile parses the JSON file and create the initial
// config value. If the argument is an empty string (i.e. the user
// has not specified the path to a configuration file) a new config value will
// be created from the default values.
func configureFromFile(file string) (PominalConfig, error) {
	if len(file) == 0 {
		config := PominalConfig{
			MaxWorkSessions: defaultMaxWorkSessions,
			Sessions: Sessions{
				Work: SessionConfig{
					Duration: defaultWorkTime,
				},
				ShortBreak: SessionConfig{
					Duration: defaultShortBreakTime,
				},
				LongBreak: SessionConfig{
					Duration: defaultLongBreakTime,
				},
			},
		}

		return config, nil
	}

	f, err := os.Open(file)
	if err != nil {
		return PominalConfig{}, err
	}

	defer f.Close()

	dec := json.NewDecoder(f)
	config := PominalConfig{}

	if err := dec.Decode(&config); err != nil {
		return PominalConfig{}, err
	}

	return config, nil
}

// configureFlagOverrides returns the config value where the
// command-line flags override the corresponding fields in the
// config value. Right now the session durations and the maximum
// work sessions can be overridden.
func configureFlagOverrides(config PominalConfig, workTime, shortBreakTime, longBreakTime string, maxWorkSessions int) PominalConfig {
	if len(workTime) > 0 {
		config.Sessions.Work.Duration = workTime
	}

	if len(shortBreakTime) > 0 {
		config.Sessions.ShortBreak.Duration = shortBreakTime
	}

	if len(longBreakTime) > 0 {
		config.Sessions.LongBreak.Duration = longBreakTime
	}

	if maxWorkSessions > 0 {
		config.MaxWorkSessions = maxWorkSessions
	}

	return config
}