package device

import (
    "time"
    "bytes"
    "text/template"
    "fmt"
)

type DayOfWeek int

func (d DayOfWeek) Next() DayOfWeek {
    if d == Sunday {
        return Monday
    }
    return d+1
}

func (d DayOfWeek) Previous() DayOfWeek {
    if d == Monday {
        return Sunday
    }
    return d-1
}

func (d DayOfWeek) DurationBetween(n DayOfWeek) time.Duration {
    // return duration between two day of week
    var duration time.Duration
    if (d-n == 0) {
        duration, _ = time.ParseDuration("168h")
    } else {
        duration, _ = time.ParseDuration(fmt.Sprintf("%dh", (d-n)*24 ))
    }
    return duration
}


const (
    Monday DayOfWeek = 0
    Thuesday         = 1
    Wednesday        = 2
    Thursday         = 3
    Friday           = 4
    Saturday         = 5
    Sunday           = 6
)

func WeekDayEnToFr(weekday time.Weekday) DayOfWeek {
    // translate weekday to french week, start by Monday
    return map[time.Weekday]DayOfWeek {
        time.Monday : Monday,
        time.Tuesday : Thuesday,
        time.Wednesday: Wednesday,
        time.Thursday : Thursday,
        time.Friday: Friday,
        time.Saturday: Saturday,
        time.Sunday: Sunday,
    }[weekday]
}

func daytime(t time.Time) int {
    return t.Hour()*60 + t.Minute()
}

func weekday(t time.Time) DayOfWeek {
    return WeekDayEnToFr(t.Weekday())
}

type Message struct {
    Payload []byte
    Topic string
    Retain bool
}

type Setpoint struct {
    Start     int `json:"start"`
    Preset_id int `json:"preset_id"`
}

type WeekProgram map[DayOfWeek][]Setpoint

func (p WeekProgram) Current() Setpoint {
    // return current Setpoint
    now := time.Now()
    weekday := weekday(now)
    daytime := daytime(now)
    setpoint := Setpoint{}
    for _, sp := range p[weekday] {
        if daytime < sp.Start {
            break
        }
        setpoint = sp
    }
    return setpoint
}

func (p WeekProgram) NextTime(t time.Time) (time.Time, error) {
    // return next program change
    setpoint := Setpoint{}
    var next time.Time

    weekday := weekday(t)
    daytime := daytime(t)

    // Recursive func to find setpoint on weekday
    get := func (weekday DayOfWeek, daytime int) Setpoint {
        setpoint := Setpoint{}
        for _, sp := range p[weekday] {
            setpoint = sp
            if daytime < sp.Start {
                return setpoint
            }
        }
        return Setpoint{}
    }

    startweekday := weekday
    for (setpoint == Setpoint{}) {
        setpoint = get(weekday, daytime)
        if (setpoint != Setpoint{}) {
            // setpoint found, compute time
            next := t.Add( startweekday.DurationBetween(weekday) )
            next = t.Add( time.Duration(setpoint.Start - daytime ) * time.Minute )
            return next, nil
        }
        weekday = weekday.Next()
        daytime = 0
        if weekday == startweekday {
            return next, fmt.Errorf("Shouldn't happen no setpoint found over the week")
        }
    }

    return next, nil
}

type Programs map[string]WeekProgram

type Preset struct {
    Label string `json:"label"`
    Value int    `json:"value"`
    Color string `json:"color"`
}

type TVRSettings struct {
    Setpoint_topic       string `json:"setpoint_topic"`
    Setpoint_payload     string `json:"setpoint_payload"`
    Setpoint_state_topic string `json:"setpoint_state_topic"`
    Setpoint_state_jp    string `json:"setpoint_state_jp"`
}

func (s TVRSettings) FormatTopicState(device_name string) (string, error) {
    type Variable struct {
        Device string
    }
    variables := Variable{device_name}
    t, err := template.New("topic").Parse(s.Setpoint_state_topic)
    if err != nil {
        return "", err
    }
    buf := new(bytes.Buffer)
    err = t.Execute(buf, variables)
    if err != nil {
        return "", err
    }
    return buf.String(), nil
}

func (s TVRSettings) FormatTopic(device_name string) (string, error) {
    type Variable struct {
        Device string
    }
    variables := Variable{device_name}
    t, err := template.New("topic").Parse(s.Setpoint_topic)
    if err != nil {
        return "", err
    }
    buf := new(bytes.Buffer)
    err = t.Execute(buf, variables)
    if err != nil {
        return "", err
    }
    return buf.String(), nil
}

func (s TVRSettings) FormatPayload(setpoint int) (string, error) {
    type Variable struct {
        Setpoint int
    }
    variables := Variable{setpoint}
    t, err := template.New("payload").Parse(s.Setpoint_payload)
    if err != nil {
        return "", err
    }
    buf := new(bytes.Buffer)
    err = t.Execute(buf, variables)
    if err != nil {
        return "", err
    }
    return buf.String(), nil
}

type DeviceSettings struct {
    Programs Programs `json:"programs"`
    Presets []Preset  `json:"presets"`
    TVR TVRSettings   `json:"TVR"`
}