type node_type =
    | Leaf
    | Tag
    | Other

let node_type_to_yojson = function
    | Leaf -> `String "leaf"
    | Tag -> `String "tag"
    | Other -> `String "other"

type value_constraint =
    | Regex of string [@name "regex"]
    | External of string * string option [@name "exec"]
    [@@deriving yojson]

type completion_help_type =
    | List of string [@name "list"]
    | Path of string [@name "path"]
    | Script of string [@name "script"]
    [@@deriving to_yojson]

type ref_node_data = {
    node_type: node_type;
    constraints: value_constraint list;
    constraint_error_message: string;
    completion_help: completion_help_type list;
    help: string;
    value_help: (string * string) list;
    multi: bool;
    valueless: bool;
    owner: string option;
    priority: string option;
    default_value: string option;
    hidden: bool;
    secret: bool;
} [@@deriving to_yojson]

type t = ref_node_data Vytree.t [@@deriving to_yojson]

exception Bad_interface_definition of string

exception Validation_error of string

let default_data = {
    node_type = Other;
    constraints = [];
    constraint_error_message = "Invalid value";
    completion_help = [];
    help = "No help available";
    value_help = [];
    multi = false;
    valueless = false;
    owner = None;
    priority = None;
    default_value = None;
    hidden = false;
    secret = false;
}

let default = Vytree.make default_data ""

(* Loading from XML *)

let node_type_of_string s =
    match s with
    | "node" -> Other
    | "tagNode" -> Tag
    | "leafNode" -> Leaf
    | _ -> raise (Bad_interface_definition
                  (Printf.sprintf "node, tagNode, or leafNode expected, %s found" s))

let completion_help_type_of_string v s =
    match v with
    | "list" -> List s
    | "path" -> Path s
    | "script" -> Script s
    | _ -> raise (Bad_interface_definition
                  (Printf.sprintf "list, path, or script expected, %s found" s))

(** Find a child node in xml-lite *)
let find_xml_child name xml =
    let find_aux e =
        match e with
        | Xml.Element (name', _, _) when name' = name -> true
        | _ -> false
    in
    match xml with
    | Xml.Element (_, _, children) -> Vylist.find find_aux children
    | Xml.PCData _ -> None

(* handle possible empty elements *)
let try_pcdata x =
    match x with
    | [] -> ""
    | _ ->
    try
        Xml.pcdata (List.hd x)
    with Xml.Not_pcdata _ -> ""

let get_pcdata_child name xml =
    let c = find_xml_child name xml in
    match c with
    | Some Xml.Element(_, _, x_data) -> try_pcdata x_data
    | _ -> raise (Bad_interface_definition (Printf.sprintf "No child named %s" name))

let load_value_help_from_xml d x =
    let fmt = get_pcdata_child "format" x in
    let descr = get_pcdata_child "description" x in
    let vhs = d.value_help in
    let vhs' = (fmt, descr) :: vhs in
    {d with value_help=vhs'}

let load_completion_help_from_xml d c =
    let res =
    let aux l c =
        match c with
        | Xml.Element (_, _, [Xml.PCData s]) ->
                l @ [completion_help_type_of_string (Xml.tag c) s]
        | _ -> raise (Bad_interface_definition "Malformed completion help")
    in Xml.fold aux [] c in
    let l = d.completion_help in
    let l' = l @ res in
    {d with completion_help=l'}

let load_constraint_from_xml d c =
    let aux d c =
        match c with
        | Xml.Element ("regex", _, [Xml.PCData s]) ->
            let cs = (Regex s) :: d.constraints in
            {d with constraints=cs}
        | Xml.Element ("validator", [("name", n); ("argument", a)], _) ->
            let cs = (External (n, Some a)) :: d.constraints in
            {d with constraints=cs}
        | Xml.Element ("validator", [("name", n)], _) ->
            let cs = (External (n, None)) :: d.constraints in
            {d with constraints=cs}
        | _ -> raise (Bad_interface_definition "Malformed constraint")
    in Xml.fold aux d c

let data_from_xml d x =
    let aux d x =
        match x with
        | Xml.Element ("help", _, [Xml.PCData s]) -> {d with help=s}
        | Xml.Element ("valueHelp", _, _) -> load_value_help_from_xml d x
        | Xml.Element ("completionHelp", _, _) ->
            load_completion_help_from_xml d x
        | Xml.Element ("multi", _, _) -> {d with multi=true}
        | Xml.Element ("valueless", _, _) -> {d with valueless=true}
        | Xml.Element ("constraintErrorMessage", _, [Xml.PCData s]) ->
            {d with constraint_error_message=s}
        | Xml.Element ("constraint", _, _) -> load_constraint_from_xml d x
        | Xml.Element ("priority", _, [Xml.PCData i]) ->
            {d with priority=Some i}
        | Xml.Element ("hidden", _, _) -> {d with hidden=true}
        | Xml.Element ("secret", _, _) -> {d with secret=true}
        | _ -> raise (Bad_interface_definition "Malformed property tag")
    in Xml.fold aux d x

let rec insert_from_xml basepath reftree xml =
    match xml with
    | Xml.Element ("syntaxVersion", _, _) -> reftree
    | Xml.Element (_, _,  _) ->
        let props = find_xml_child "properties" xml in
        let data =
            (match props with
            | None -> default_data
            | Some p -> data_from_xml default_data p)
        in
        let node_type = node_type_of_string (Xml.tag xml) in
        let node_owner = try let o = Xml.attrib xml "owner" in Some o
                         with _ -> None
        in
        let default_value_elem = find_xml_child "defaultValue" xml in
        let default_value =
            (match default_value_elem with
            | Some (Xml.Element (_, _, [Xml.PCData s])) -> Some s
            | _ -> None)
        in
        let data = {data with node_type=node_type; owner=node_owner; default_value=default_value} in
        let name = Xml.attrib xml "name" in
        let path = basepath @ [name] in
        let new_tree = Vytree.insert_maybe reftree path data in
        (match node_type with
        | Leaf -> new_tree
        | _ ->
            let children = find_xml_child "children" xml in
            (match children with
             | None -> raise (Bad_interface_definition (Printf.sprintf "Node %s has no children" name))
             | Some c ->  List.fold_left (insert_from_xml path) new_tree (Xml.children c)))
    | _ -> raise (Bad_interface_definition "PCData not allowed here")

let load_from_xml reftree file =
    let xml_to_reftree xml reftree =
        match xml with
        | Xml.Element ("interfaceDefinition", _, children) ->
            List.fold_left (insert_from_xml []) reftree children
        | _ -> raise (Bad_interface_definition "Should start with <interfaceDefinition>")
    in
    try
        let xml = Xml.parse_file file in
        xml_to_reftree xml reftree
    with
    | Xml.File_not_found msg -> raise (Bad_interface_definition msg)
    | Xml.Error e -> raise (Bad_interface_definition (Xml.error e))

let is_multi reftree path =
    let data = Vytree.get_data reftree path in
    data.multi

let is_hidden reftree path =
    let data = Vytree.get_data reftree path in
    data.hidden

let is_secret reftree path =
    let data = Vytree.get_data reftree path in
    data.secret

let is_tag reftree path =
    let data = Vytree.get_data reftree path in
    match data.node_type with
    | Tag -> true
    | _ -> false

let is_leaf reftree path =
    let data = Vytree.get_data reftree path in
    match data.node_type with
    | Leaf -> true
    | _ -> false

let is_valueless reftree path =
    let data = Vytree.get_data reftree path in
    data.valueless

let get_owner reftree path =
    let data = Vytree.get_data reftree path in
    data.owner

let get_help_string reftree path =
    let data = Vytree.get_data reftree path in
    data.help

let get_value_help reftree path =
    let data = Vytree.get_data reftree path in
    data.value_help

let get_completion_data reftree path =
    let aux node =
        let data = Vytree.data_of_node node in
        (data.node_type, data.multi, data.help)
    in List.map aux (Vytree.children_of_node @@ Vytree.get reftree path)

module JSONRenderer =
struct
    let render_data data =
        ref_node_data_to_yojson data |> Yojson.Safe.to_string

    let rec render_node node =
        let name = Vytree.name_of_node node in
        let children = Vytree.children_of_node node in
        let data = Vytree.data_of_node node in
        let data_str = render_data data in
        let children_strs = List.map render_node children in
        let children_str = String.concat "," children_strs in
        if children_str <> "" then
            Printf.sprintf "\"%s\": {\"node_data\": %s, %s}" name data_str children_str
        else
            Printf.sprintf "\"%s\": {\"node_data\": %s}" name data_str

    let render_json node =
        let data = Vytree.data_of_node node in
        let data_str = render_data data in
        let children = Vytree.children_of_node node in
        let child_configs = List.map render_node children in
        let child_config = String.concat "," child_configs in
        Printf.sprintf "{\"node_data\": %s, %s}" data_str child_config
end (* JSONRenderer *)

let render_json = JSONRenderer.render_json