# Information about all variables
variables = ref([])

# Float variables
variables_float = ref([])

# Int variables
variables_int = ref([])

# Bool variables
variables_bool = ref([])

# String variables
variables_string = ref([])

# Unit variables: those are not references but handler functions
variables_unit = ref([])
let interactive = ()
let interactive.float = ()
let interactive.int = ()
let interactive.bool = ()
let interactive.string = ()
let interactive.unit = ()
let interactive.error = error.register("interactive.error")

# @flag hidden
def interactive.list(_) =
  l = variables()
  l =
    list.map(
      fun (xv) ->
        begin
          let (x, v) = xv
          "#{x} : #{v.type}"
        end,
      l
    )

  string.concat(separator="\n", l)
end

server.register(
  usage="list",
  description=
    "List available interactive variables.",
  namespace="var",
  "list",
  interactive.list
)

# Description of an interactive variable.
# @flag hidden
def interactive.description(name) =
  list.assoc(name, variables()).description
end

# Type of an interactive variable.
# @flag hidden
def interactive.type(name) =
  list.assoc(name, variables()).type
end

# @flag hidden
def interactive.float.ref(name) =
  list.assoc(name, variables_float()).ref
end

# @flag hidden
def interactive.int.ref(name) =
  list.assoc(name, variables_int()).ref
end

# @flag hidden
def interactive.bool.ref(name) =
  list.assoc(name, variables_bool()).ref
end

# @flag hidden
def interactive.string.ref(name) =
  list.assoc(name, variables_string()).ref
end

# @flag hidden
def interactive.unit.handler(name) =
  list.assoc(name, variables_unit()).handler
end

# @flag hidden
def interactive.remove(name) =
  variables := list.assoc.remove.all(name, variables())
end

# Remove an interactive variable.
# @param name Name of the variable.
# @category Interaction
# @flag hidden
def interactive.float.remove(name) =
  interactive.remove(name)
  variables_float := list.assoc.remove.all(name, variables_float())
end

# Remove an interactive variable.
# @param name Name of the variable.
# @category Interaction
# @flag hidden
def interactive.int.remove(name) =
  interactive.remove(name)
  variables_int := list.assoc.remove.all(name, variables_int())
end

# Remove an interactive variable.
# @param name Name of the variable.
# @category Interaction
# @flag hidden
def interactive.bool.remove(name) =
  interactive.remove(name)
  variables_bool := list.assoc.remove.all(name, variables_bool())
end

# Remove an interactive variable.
# @param name Name of the variable.
# @category Interaction
# @flag hidden
def interactive.string.remove(name) =
  interactive.remove(name)
  variables_string := list.assoc.remove.all(name, variables_string())
end

# Remove an interactive variable.
# @param name Name of the variable.
# @category Interaction
# @flag hidden
def interactive.unit.remove(name) =
  interactive.remove(name)
  variables_unit := list.assoc.remove.all(name, variables_unit())
end

# Function called to ensure persistency of data.
let interactive.persistency = ref(fun () -> ())

# @flag hidden
def interactive.float.set(name, v) =
  interactive.float.ref(name) := v
  p = interactive.persistency()
  p()
end

# @flag hidden
def interactive.int.set(name, v) =
  interactive.int.ref(name) := v
  p = interactive.persistency()
  p()
end

# @flag hidden
def interactive.bool.set(name, v) =
  interactive.bool.ref(name) := v
  p = interactive.persistency()
  p()
end

# @flag hidden
def interactive.string.set(name, v) =
  interactive.string.ref(name) := v
  p = interactive.persistency()
  p()
end

# @flag hidden
def interactive.unit.set(name) =
  f = interactive.unit.handler(name)
  f()
end

%ifdef osc.on_float
let stdlib_osc = osc
%endif

# Create an interactive variable.
# @flag hidden
# @param ~name Name of the variable.
# @param ~description Description of the variable.
# @param ~osc OSC address for the variable.
# @param ~type Type of the variable.
def interactive.create(~name, ~description="", ~osc="", ~type) =
  if
    list.assoc.mem(name, variables())
  then
    error.raise(
      interactive.error,
      "variable already registered"
    )
  end

  variables := (name, {type=type, description=description})::variables()
  variables :=
    list.sort(
      fun (n, n') -> if fst(n) < fst(n') then -1 else 1 end, variables()
    )

%ifdef osc.on_float
  if
    osc != ""
  then
    if
      type == "float"
    then
      stdlib_osc.on_float(osc, fun (x) -> interactive.float.set(name, x))
    elsif
      type == "int"
    then
      stdlib_osc.on_int(osc, fun (x) -> interactive.int.set(name, x))
    elsif
      type == "bool"
    then
      stdlib_osc.on_bool(osc, fun (x) -> interactive.bool.set(name, x))
    elsif
      type == "string"
    then
      stdlib_osc.on_string(osc, fun (x) -> interactive.string.set(name, x))
    elsif type == "unit" then ()
    else
      # TODO
      error.raise(error.not_found)
    end
  end
%else
  ignore(osc)
%endif
end

# @flag hidden
def interactive.get(name) =
  try
    t = interactive.type(name)
    if
      t == "float"
    then
      r = interactive.float.ref(name)
      string.float(decimal_places=3, r())
    elsif
      t == "int"
    then
      r = interactive.int.ref(name)
      string(r())
    elsif
      t == "bool"
    then
      r = interactive.bool.ref(name)
      string(r())
    elsif
      t == "string"
    then
      r = interactive.string.ref(name)
      r()
    elsif t == "unit" then "()"
    else
      error.raise(error.not_found)
    end
  catch _ do
    "Variable not found."
  end
end

server.register(
  namespace="var",
  description=
    "Get the value of a variable.",
  "get",
  interactive.get
)

# @flag hidden
def interactive.set(arg) =
  try
    arg = r/=/.split(arg)
    name = string.trim(list.nth(arg, 0))
    value = string.trim(list.nth(arg, 1))
    t = interactive.type(name)
    if
      t == "float"
    then
      interactive.float.set(name, float_of_string(value))
    elsif t == "int" then interactive.int.set(name, int_of_string(value))
    elsif t == "bool" then interactive.bool.set(name, bool_of_string(value))
    elsif t == "string" then interactive.string.set(name, value)
    elsif t == "unit" then interactive.unit.set(name)
    else
      error.raise(error.not_found)
    end

    "Variable #{name} set."
  catch _ do
    "Syntax error or variable not found."
  end
end

server.register(
  usage=
    "set <name> = <value>",
  description=
    "Set the value of a variable.",
  namespace="var",
  "set",
  interactive.set
)

# Save the value of all interactive variables in a file.
# @category Interaction
# @flag extra
# @param fname Name of the file.
def interactive.save(fname) =
  data =
    json.stringify(
      {
        float=
          list.map(
            fun (nv) ->
              begin
                let (name, v) = nv
                (name, v.ref())
              end,
            variables_float()
          ),
        int=
          list.map(
            fun (nv) ->
              begin
                let (name, v) = nv
                (name, v.ref())
              end,
            variables_int()
          ),
        bool=
          list.map(
            fun (nv) ->
              begin
                let (name, v) = nv
                (name, v.ref())
              end,
            variables_bool()
          ),
        string=
          list.map(
            fun (nv) ->
              begin
                let (name, v) = nv
                (name, v.ref())
              end,
            variables_string()
          )
      }
    )

  file.write(data=data, fname)
end

# Load the value of interactive variables from a file.
# @category Interaction
# @flag extra
# @param fname Name of the file.
def interactive.load(fname) =
  vars = file.contents(fname)
  let json.parse (vars :
    {
      float: [(string*float)],
      int: [(string*int)],
      bool: [(string*bool)],
      string: [(string*string)]
    }
  ) = vars

  list.iter(
    fun (nv) ->
      try
        interactive.float.set(fst(nv), snd(nv))
      catch _ do
        log.important(
          label="interactive.load",
          "Variable #{fst(nv)} not found."
        )
      end,
    vars.float
  )

  list.iter(
    fun (nv) ->
      try
        interactive.int.set(fst(nv), snd(nv))
      catch _ do
        log.important(
          label="interactive.load",
          "Variable #{fst(nv)} not found."
        )
      end,
    vars.int
  )

  list.iter(
    fun (nv) ->
      try
        interactive.bool.set(fst(nv), snd(nv))
      catch _ do
        log.important(
          label="interactive.load",
          "Variable #{fst(nv)} not found."
        )
      end,
    vars.bool
  )

  list.iter(
    fun (nv) ->
      try
        interactive.string.set(fst(nv), snd(nv))
      catch _ do
        log.important(
          label="interactive.load",
          "Variable #{fst(nv)} not found."
        )
      end,
    vars.string
  )
end

# Make the value of interactive variables persistent: they are loaded from the
# given file and stored there whenever updated. This function should be called
# after all interactive variables have been defined (variables not declared yet
# will not be loaded).
# @category Interaction
# @flag extra
# @param fname Name of the file.
def interactive.persistent(fname) =
  if
    file.exists(fname)
  then
    interactive.load(fname)
  else
    interactive.save(fname)
  end

  interactive.persistency := {interactive.save(fname)}
end

# Expose interactive variables through harbor http server. Once this is called,
# with default parameters, you can browse <http://localhost:8000/interactive> to
# change the value of interactive variables using sliders.
# @category Interaction
# @flag extra
# @param ~port Port of the server.
# @param ~transport Http transport. Use `http.transport.ssl` or http.transport.secure_transport`, when available, to enable HTTPS output
# @param ~uri URI of the server.
def interactive.harbor(
  ~transport=http.transport.unix,
  ~port=8000,
  ~uri="/interactive"
) =
  def webpage(request, response) =
    form_data = request.data
    data = ref("")

    def add(s) =
      data := data() ^ s ^ "\n"
    end

    title =
      "Interactive values"
    add(
      "<!DOCTYPE html><html><head>"
    )
    add(
      "<meta charset='utf-8'/>"
    )
    add("<title>#{title}</title>")
    add(
      "<style>
    body {
      font-family: sans-serif;
    }
    h1 {
      text-align: center;
    }
    form {
      border-radius: 20px;
      display: block;
      background-color: whitesmoke;
      width: max-content;
      margin: 0 auto;
      padding: 2ex;
      display:grid;
      grid-template-columns: max-content max-content;
      grid-gap: 5px;
    }
    label {
      text-align: right;
    }
    input {
      width: 300px;
    }
    </style>"
    )

    # TODO: we could send only the updated value instead of sending them all
    add(
      "<script>
    function send() {
      let interactive = document.getElementsByClassName('interactive');
      let data = '';
      for(var i=0; i<interactive.length; i++){
        if (interactive[i].type == 'checkbox') {
          if (interactive[i].checked) {
            interactive[i].value = 'true'
          } else {
            interactive[i].value = 'false'
          }
        }
        if (interactive[i].type != 'button') {
          data = data.concat(interactive[i].name+'='+encodeURIComponent(interactive[i].value))+'&';
        }
      }
      console.log('Posting: ' + data);
      let xmlHttp = new XMLHttpRequest();
      xmlHttp.open('POST', '#{
        uri
      }');
      xmlHttp.onreadystatechange = function () {
        if(xmlHttp.readyState === XMLHttpRequest.DONE) {
          var status = xmlHttp.status;
          if (status === 0 || (status >= 200 && status < 400)) {
            //console.log(xmlHttp.responseText);
          } else {
            console.log('Failed to send values.')
          }
        }
      }
      xmlHttp.send(data);
    }
    function sendUnit(name) {
      const body = name + '=';
      console.log('Posting: ' + body);
      fetch('#{
        uri
      }', {method: 'POST', body: body});
    }
    </script>"
    )

    add("</head><body>")
    add("<h1>#{title}</h1>")

    def add_var(nv) =
      let (name, v) = nv
      description = interactive.description(name)
      description =
        if
          description == ""
        then
          name
        else
          "#{description} (#{name})"
        end

      add(
        "<label for=#{name}>#{string.escape.html(description)}</label>"
      )
      common =
        "id='#{name}' name='#{name}' class='interactive' onchange=\"send()\""

      if
        v.type == "float"
      then
        v = list.assoc(name, variables_float())
        value = http.string_of_float(v.ref())
        if
          v.min == 0. - infinity or v.max == infinity
        then
          add(
            "<input type='number' #{common} step='#{v.step}' value='#{value}'>"
          )
        else
          min = http.string_of_float(v.min)
          max = http.string_of_float(v.max)
          step = http.string_of_float(v.step)
          value = http.string_of_float(v.ref())
          unit =
            if
              v.unit == ""
            then
              ""
            else
              " " ^
                v.unit
            end
          add(
            "<div><input type='range' #{common} min='#{min}' max='#{max}' step='#{
              step
            }' value='#{value}' oninput='document.getElementById(\"#{
              name
            }-value\").innerHTML = this.value+\"#{unit}\"'><text id='#{
              name
            }-value' style='inline'>#{value}#{unit}</text></div>"
          )
        end
      elsif
        v.type == "int"
      then
        v = list.assoc(name, variables_int())
        value = string(v.ref())
        add(
          "<input type='number' #{common} step='1' value='#{value}'>"
        )
      elsif
        v.type == "bool"
      then
        v = list.assoc(name, variables_bool())
        c = (v.ref()) ? "checked" : ""
        add(
          "<input type='checkbox' #{common} value='true' #{c}>"
        )
      elsif
        v.type == "string"
      then
        v = list.assoc(name, variables_string())
        add(
          "<input type='text' #{common} value='#{string.escape.html(v.ref())}'>"
        )
      elsif
        v.type == "unit"
      then
        add(
          "<button type='button' #{common} onclick=\"sendUnit('#{name}')\">#{
            name
          }</button>"
        )
      else
        ()
      end
    end

    add("<form>")
    list.iter(add_var, variables())
    add("</form>")
    add("</body>")
    response.html(data())
  end

  harbor.http.register(
    transport=transport, port=port, method="GET", uri, webpage
  )

  def setter(request, _) =
    data = url.split_args(request.body())

    def update(nv) =
      let (name, v) = nv
      try
        t = interactive.type(name)
        if
          t == "float"
        then
          interactive.float.set(name, float_of_string(v))
        elsif t == "int" then interactive.int.set(name, int_of_string(v))
        elsif t == "bool" then interactive.bool.set(name, bool_of_string(v))
        elsif t == "string" then interactive.string.set(name, v)
        elsif t == "unit" then interactive.unit.set(name)
        end
      catch e do
        log.important(
          label="interactive.harbor",
          "Could not update variable #{name} (#{e.kind}: #{e.message})."
        )
      end
    end

    list.iter(update, data)
  end

  harbor.http.register(
    transport=transport, port=port, method="POST", uri, setter
  )

  log.important(
    label="interactive.harbor",
    "Website should be ready at <http://localhost:#{port}#{uri}>."
  )
end

# Read a float from an interactive input.
# @category Interaction
# @flag extra
# @param ~min Minimal value.
# @param ~max Maximal value.
# @param ~step Typical variation of the value.
# @param ~description Description of the variable.
# @param ~unit Unit for the variable.
# @param ~osc OSC address.
# @param name Name of the variable.
# @param v Initial value.
def replaces interactive.float(
  ~min=0. - infinity,
  ~max=infinity,
  ~step=0.1,
  ~description="",
  ~unit="",
  ~osc="",
  name,
  v
) =
  interactive.create(name=name, description=description, osc=osc, type="float")
  r = ref(v)
  variables_float :=
    (name, {ref=r, unit=unit, min=min, max=max, step=step})::variables_float()

  r.{
    set=fun (x) -> interactive.float.set(name, x),
    remove={interactive.float.remove(name)}
  }
end

# Read an integer from an interactive input.
# @category Interaction
# @flag extra
# @param ~description Description of the variable.
# @param ~osc OSC address.
# @param name Name of the variable.
# @param v Initial value.
def replaces interactive.int(~description="", ~osc="", name, v) =
  interactive.create(name=name, description=description, osc=osc, type="int")
  r = ref(v)
  variables_int := (name, {ref=r})::variables_int()
  r.{
    set=fun (x) -> interactive.int.set(name, x),
    remove={interactive.int.remove(name)}
  }
end

# Read a boolean from an interactive input.
# @category Interaction
# @flag extra
# @param ~description Description of the variable.
# @param ~osc OSC address.
# @param name Name of the variable.
# @param v Initial value.
def replaces interactive.bool(~description="", ~osc="", name, v) =
  interactive.create(name=name, description=description, osc=osc, type="bool")
  r = ref(v)
  variables_bool := (name, {ref=r})::variables_bool()
  r.{
    set=fun (x) -> interactive.bool.set(name, x),
    remove={interactive.bool.remove(name)}
  }
end

# Read a string from an interactive input.
# @category Interaction
# @flag extra
# @param ~description Description of the variable.
# @param ~osc OSC address.
# @param name Name of the variable.
# @param v Initial value.
def replaces interactive.string(~description="", ~osc="", name, v) =
  interactive.create(name=name, description=description, osc=osc, type="string")
  r = ref(v)
  variables_string := (name, {ref=r})::variables_string()
  r.{
    set=fun (x) -> interactive.string.set(name, x),
    remove={interactive.string.remove(name)}
  }
end

# Register a callback when a unit interactive input is set.
# @category Interaction
# @flag extra
# @param ~description Description of the variable.
# @param ~osc OSC address.
# @param name Name of the variable.
# @param f Function triggered when the value is set.
def replaces interactive.unit(~description="", ~osc="", name, f) =
  interactive.create(name=name, description=description, osc=osc, type="unit")
  variables_unit := (name, {handler=f})::variables_unit()
  {set=f, remove={interactive.float.remove(name)}}
end

# Create a multiband compressor whose parameters are interactive variables.
# @category Interaction
# @flag extra
# @param ~id Id of the source. Variable names are prefixed with this.
# @param ~bands Number of bands.
# @param s Source to compress.
def compress.multiband.interactive(~id=null, ~bands=5, s) =
  id = string.id.default(default="compress.multiband.interactive", id)
  prefix = id ^ "_"
  wet = interactive.float(prefix ^ "wet", min=0., max=1., 1.)
  min_freq = 100.
  max_freq = 15000.

  def band(i) =
    frequency =
      exp(
        (ln(max_freq) - ln(min_freq)) * float_of_int(i) /
          float_of_int(bands - 1) +
          ln(min_freq)
      )

    log.important(
      label=id,
      "Adding a band at #{frequency} Hz."
    )
    frequency =
      interactive.float(
        "#{prefix}frequency#{i}",
        unit="Hz",
        min=0.,
        max=20000.,
        step=10.,
        frequency
      )

    attack =
      interactive.float(
        "#{prefix}attack#{i}", unit="ms", min=0., max=1000., step=10., 100.
      )

    release =
      interactive.float(
        "#{prefix}release#{i}", unit="ms", min=0., max=1000., step=10., 200.
      )

    threshold =
      interactive.float(
        "#{prefix}threshold#{i}", unit="dB", min=-20., max=0., step=0.1, -10.
      )

    ratio =
      interactive.float("#{prefix}ratio#{i}", min=1., max=10., step=0.1, 4.)

    gain =
      interactive.float(
        "#{prefix}gain#{i}", unit="dB", min=0., max=30., step=0.1, 3.
      )

    {
      frequency=frequency,
      attack=attack,
      release=release,
      threshold=threshold,
      ratio=ratio,
      gain=gain
    }
  end

  l = list.init(bands, band)
  compress.multiband(wet=wet, s, l)
end