using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using ServiceStack.Script;
using ServiceStack.Text;
using ServiceStack.Text.Common;
using ServiceStack.Web;

namespace ServiceStack.Script;

// ReSharper disable InconsistentNaming
public partial class DefaultScripts
{
    internal IRequest req(ScriptScopeContext scope) => scope.GetValue(ScriptConstants.Request) as IRequest;

    public bool matchesPathInfo(ScriptScopeContext scope, string pathInfo) => 
        scope.GetValue("PathInfo")?.ToString().TrimEnd('/') == pathInfo?.TrimEnd('/');

    public bool startsWithPathInfo(ScriptScopeContext scope, string pathInfo) => pathInfo == "/"
        ? matchesPathInfo(scope, pathInfo)
        : scope.GetValue("PathInfo")?.ToString().TrimEnd('/').StartsWith(pathInfo?.TrimEnd('/') ?? "") == true;

    public object ifMatchesPathInfo(ScriptScopeContext scope, object returnTarget, string pathInfo) =>
        matchesPathInfo(scope, pathInfo) ? returnTarget : null;

    public bool isHttpGet(ScriptScopeContext scope) => req(scope)?.Verb == HttpMethods.Get;
    public bool isHttpPost(ScriptScopeContext scope) => req(scope)?.Verb == HttpMethods.Post;
    public bool isHttpPut(ScriptScopeContext scope) => req(scope)?.Verb == HttpMethods.Put;
    public bool isHttpDelete(ScriptScopeContext scope) => req(scope)?.Verb == HttpMethods.Delete;
    public bool isHttpPatch(ScriptScopeContext scope) => req(scope)?.Verb == HttpMethods.Patch;

    public object ifHttpGet(ScriptScopeContext scope, object ignoreTarget) => ifHttpGet(scope);
    public object ifHttpGet(ScriptScopeContext scope) => isHttpGet(scope) ? (object)IgnoreResult.Value : StopExecution.Value;
    public object ifHttpPost(ScriptScopeContext scope, object ignoreTarget) => ifHttpPost(scope);
    public object ifHttpPost(ScriptScopeContext scope) => isHttpPost(scope) ? (object)IgnoreResult.Value : StopExecution.Value;
    public object ifHttpPut(ScriptScopeContext scope, object ignoreTarget) => ifHttpPut(scope);
    public object ifHttpPut(ScriptScopeContext scope) => isHttpPut(scope) ? (object)IgnoreResult.Value : StopExecution.Value;
    public object ifHttpDelete(ScriptScopeContext scope, object ignoreTarget) => ifHttpDelete(scope);
    public object ifHttpDelete(ScriptScopeContext scope) => isHttpDelete(scope) ? (object)IgnoreResult.Value : StopExecution.Value;
    public object ifHttpPatch(ScriptScopeContext scope, object ignoreTarget) => ifHttpPatch(scope);
    public object ifHttpPatch(ScriptScopeContext scope) => isHttpPatch(scope) ? (object)IgnoreResult.Value : StopExecution.Value;

    public object importRequestParams(ScriptScopeContext scope)
    {
        var args = RequestScriptUtils.GetRequestParams(req(scope));
        foreach (var entry in args)
        {
            scope.ScopedParams[entry.Key] = entry.Value;
        }
        return StopExecution.Value;
    }

    public object importRequestParams(ScriptScopeContext scope, IEnumerable onlyImportArgNames)
    {
        var args = RequestScriptUtils.GetRequestParams(req(scope));
        var names = toVarNames(onlyImportArgNames);
        foreach (var name in names)
        {
            if (args.TryGetValue(name, out var value))
                scope.ScopedParams[name] = value;

        }
        return StopExecution.Value;
    }

    public Stream requestBody(ScriptScopeContext scope)
    {
        var httpReq = req(scope);
        httpReq.UseBufferedStream = true;
        return req(scope).InputStream;
    }

    public string rawBodyAsString(ScriptScopeContext scope) => req(scope).GetRawBody();
    public object rawBodyAsJson(ScriptScopeContext scope) => JSON.parse(rawBodyAsString(scope));

    public async Task<object> requestBodyAsString(ScriptScopeContext scope) => await req(scope).GetRawBodyAsync().ConfigAwait();
    public async Task<object> requestBodyAsJson(ScriptScopeContext scope) => JSON.parse(await req(scope).GetRawBodyAsync().ConfigAwait());
        
    public NameValueCollection form(ScriptScopeContext scope) => req(scope).FormData;
    public NameValueCollection query(ScriptScopeContext scope) => req(scope).QueryString;
    public NameValueCollection qs(ScriptScopeContext scope) => req(scope).QueryString;
    public string queryString(ScriptScopeContext scope)
    {
        var qs = req(scope).QueryString.ToString();
        return string.IsNullOrEmpty(qs) ? qs : "?" + qs;
    }

    public Dictionary<string, object> queryDictionary(ScriptScopeContext scope) =>
        req(scope).QueryString.ToObjectDictionary();
        
    public Dictionary<string, object> formDictionary(ScriptScopeContext scope) =>
        req(scope).FormData.ToObjectDictionary();
        
    public string toQueryString(object keyValuePairs)
    {
        var sb = StringBuilderCache.Allocate();
        var i = 0;
        if (keyValuePairs is IEnumerable<KeyValuePair<string, object>> kvps)
        {
            foreach (var entry in kvps)
            {
                if (i++ > 0)
                    sb.Append('&');

                sb.Append(entry.Key + "=" + entry.Value?.ToString().UrlEncode());
            }
        }
        else if (keyValuePairs is IDictionary d)
        {
            foreach (var key in d.Keys)
            {
                if (i++ > 0)
                    sb.Append('&');

                sb.Append(key + "=" + d[key]?.ToString().UrlEncode());
            }
        }
        else if (keyValuePairs is NameValueCollection nvc)
        {
            foreach (string key in nvc)
            {
                if (key == null)
                    continue;
                if (i++ > 0)
                    sb.Append('&');
                sb.Append(key + "=" + nvc[key].UrlEncode());
            }
        }
        else throw new NotSupportedException($"{nameof(toQueryString)} expects a collection of KeyValuePair's but was '{keyValuePairs.GetType().Name}'");
            
        return StringBuilderCache.ReturnAndFree(sb.Length > 0 ? sb.Insert(0,'?') : sb);
    }

    public Dictionary<string,object> toCoercedDictionary(object target)
    {
        var objDictionary = target.ToObjectDictionary();
        var keys = objDictionary.Keys.ToList();
        foreach (var key in keys)
        {
            var value = objDictionary[key];
            if (value is string str)
                objDictionary[key] = coerce(str);
        }
        return objDictionary;
    }

    public object coerce(string str) => DynamicNumber.TryParse(str, out var numValue)
        ? numValue
        : str.StartsWith(DateTimeSerializer.WcfJsonPrefix)
            ? DateTimeSerializer.ParseDateTime(str)
            : str.EqualsIgnoreCase(bool.TrueString)
                ? true
                : str.EqualsIgnoreCase(bool.FalseString)
                    ? false
                    : str == "null"
                        ? (object)null
                        : str;

    public string httpMethod(ScriptScopeContext scope) => req(scope)?.Verb;
    public string httpRequestUrl(ScriptScopeContext scope) => req(scope)?.AbsoluteUri;
    public string httpPathInfo(ScriptScopeContext scope) => scope.GetValue("PathInfo")?.ToString();

    public string formQuery(ScriptScopeContext scope, string name) => ViewUtils.FormQuery(req(scope), name);

    public string[] formQueryValues(ScriptScopeContext scope, string name) => ViewUtils.FormQueryValues(req(scope), name);
    public string httpParam(ScriptScopeContext scope, string name) => ViewUtils.GetParam(req(scope), name);

    public string urlEncode(string value, bool upperCase) => value.UrlEncode(upperCase);
    public string urlEncode(string value) => value.UrlEncode();
    public string urlDecode(string value) => value.UrlDecode();

    public string htmlEncode(string value) => value.HtmlEncode();
    public string htmlDecode(string value) => value.HtmlDecode();
        
    public bool containsXss(object target)
    {
        try
        {
            return MatchesStringValue(target, ContainsXss);
        }
        catch (ArgumentException)
        {
            throw new NotSupportedException($"containsXss cannot validate {target.GetType().Name}");
        }
    }

    public static bool MatchesStringValue(object target, Func<string, bool> match)
    {
        if (target == null)
            return false;

        if (target is string str)
        {
            if (match(str))
                return true;
        }
        else if (target is IDictionary d)
        {
            foreach (var item in d.Values)
            {
                if (item is string s && match(s))
                    return true;
            }
        }
        else if (target is IEnumerable objs)
        {
            foreach (var item in objs)
            {
                if (item is string s && match(s))
                    return true;
            }
        }
        else throw new ArgumentException(nameof(target));
            
        return false;
    }
        
    // tests for https://www.owasp.org/index.php/OWASP_Testing_Guide_Appendix_C:_Fuzz_Vectors#Cross_Site_Scripting_.28XSS.29
    public static string[] XssFragments = { //greedy list
        "<script",
        "javascript:",
        "%3A",       //= ':' URL Encode
        "&#0000058", //= ':' HTML Entity Encode
        "SRC=#",
        "SRC=/",
        "SRC=&",
        "SRC= ",
        "onload=",
        "onload =",
        "onunload=",
        "onerror=",
        "@import",
        ":url(",
    };

    public static bool ContainsXss(string text)
    {
        foreach (var needle in XssFragments)
        {
            var pos = text.IndexOf(needle, 0, StringComparison.OrdinalIgnoreCase);
            if (pos >= 0)
                return true;
        }
        return false;
    }
}