// =============================================================================
// Boko — Async Web Framework for Bux (inspired by FastAPI)
// =============================================================================
module Boko {

import Std::Io::{PrintLine, Print, PrintInt};
import Std::Net::{Net_Create, Net_SetReuse, Net_Bind, Net_Listen, Net_Accept, Net_Send, Net_Recv, Net_Close, Net_LastError};
import Std::String::{String_Len, String_Eq, String_StartsWith, String_Contains, String_Offset};
import Std::Task::{Task_Join, TaskHandle};

extern func bux_alloc(size: uint) -> *void;
extern func bux_strlen(s: String) -> uint;
extern func bux_strcmp(a: String, b: String) -> int;
extern func bux_strstr(haystack: String, needle: String) -> String;
extern func bux_str_slice(s: String, start: uint, len: uint) -> String;
extern func bux_str_split_count(s: String, delim: String) -> uint;
extern func bux_str_split_part(s: String, delim: String, index: uint) -> String;
extern func bux_sb_new(initial_cap: uint) -> *void;
extern func bux_sb_append(sb: *void, s: String);
extern func bux_sb_append_int(sb: *void, n: int64);
extern func bux_sb_append_char(sb: *void, c: char8);
extern func bux_sb_build(sb: *void) -> String;
extern func bux_sb_free(sb: *void);
extern func bux_base64url_encode(data: String, len: int) -> String;
extern func bux_base64url_decode(data: String, len: int, outlen: *int) -> String;

// =============================================================================
// HTTP Methods
// =============================================================================
enum HttpVerb {
    GET,
    POST,
    PUT,
    DELETE,
    PATCH,
    HEAD,
    OPTIONS,
}

// =============================================================================
// Request — parsed incoming HTTP request
// =============================================================================
struct Request {
    method: HttpVerb,
    path: String,
    body: String,
    headerKeys: *String,
    headerValues: *String,
    headerCount: int,
    queryKeys: *String,
    queryValues: *String,
    queryCount: int,
    pathParamKeys: *String,
    pathParamValues: *String,
    pathParamCount: int,
}

// =============================================================================
// Response — outgoing HTTP response
// =============================================================================
struct Response {
    statusCode: int,
    contentType: String,
    body: String,
    extraHeaders: String,
}

// =============================================================================
// App — server instance
// =============================================================================
struct App {
    port: int,
    threadCount: int,
    serverName: String,
}

// =============================================================================
// Request helpers
// =============================================================================

func Request_GetHeader(req: *Request, name: String) -> String {
    var i: int = 0;
    while i < req.headerCount {
        if bux_strcmp(req.headerKeys[i], name) == 0 {
            return req.headerValues[i];
        }
        i = i + 1;
    }
    return "";
}

func Request_GetQuery(req: *Request, name: String) -> String {
    var i: int = 0;
    while i < req.queryCount {
        if bux_strcmp(req.queryKeys[i], name) == 0 {
            return req.queryValues[i];
        }
        i = i + 1;
    }
    return "";
}

func Request_GetPathParam(req: *Request, name: String) -> String {
    var i: int = 0;
    while i < req.pathParamCount {
        if bux_strcmp(req.pathParamKeys[i], name) == 0 {
            return req.pathParamValues[i];
        }
        i = i + 1;
    }
    return "";
}

// =============================================================================
// Response constructors
// =============================================================================

func Response_New(status: int, contentType: String, body: String) -> Response {
    var resp: Response;
    resp.statusCode = status;
    resp.contentType = contentType;
    resp.body = body;
    resp.extraHeaders = "";
    return resp;
}

func Response_Ok(body: String) -> Response {
    return Response_New(200, "text/html; charset=utf-8", body);
}

func Response_Html(html: String) -> Response {
    return Response_New(200, "text/html; charset=utf-8", html);
}

func Response_Json(json: String) -> Response {
    return Response_New(200, "application/json; charset=utf-8", json);
}

func Response_Text(text: String) -> Response {
    return Response_New(200, "text/plain; charset=utf-8", text);
}

func Response_Redirect(url: String) -> Response {
    var resp: Response;
    resp.statusCode = 302;
    resp.contentType = "";
    resp.body = "";
    let sb: *void = bux_sb_new(256);
    bux_sb_append(sb, "Location: ");
    bux_sb_append(sb, url);
    bux_sb_append(sb, "\r\n");
    resp.extraHeaders = bux_sb_build(sb);
    bux_sb_free(sb);
    return resp;
}

func Response_NotFound() -> Response {
    return Response_New(404, "application/json; charset=utf-8",
        "{\"error\":\"not_found\"}");
}

func Response_Error(status: int, message: String) -> Response {
    return Response_New(status, "application/json; charset=utf-8", message);
}

func Response_NoContent() -> Response {
    return Response_New(204, "", "");
}

// =============================================================================
// Build HTTP response string from Response struct
// =============================================================================
func Response_Build(resp: Response) -> String {
    let sb: *void = bux_sb_new(2048);

    // Status line
    bux_sb_append(sb, "HTTP/1.1 ");
    bux_sb_append_int(sb, resp.statusCode as int64);
    bux_sb_append(sb, " ");
    if resp.statusCode == 200 { bux_sb_append(sb, "OK"); }
    else if resp.statusCode == 201 { bux_sb_append(sb, "Created"); }
    else if resp.statusCode == 204 { bux_sb_append(sb, "No Content"); }
    else if resp.statusCode == 302 { bux_sb_append(sb, "Found"); }
    else if resp.statusCode == 400 { bux_sb_append(sb, "Bad Request"); }
    else if resp.statusCode == 404 { bux_sb_append(sb, "Not Found"); }
    else if resp.statusCode == 500 { bux_sb_append(sb, "Internal Server Error"); }
    else { bux_sb_append(sb, "OK"); }
    bux_sb_append(sb, "\r\n");

    // Server
    bux_sb_append(sb, "Server: Boko/0.1.0 (Bux)\r\n");

    // Extra headers (redirects, CORS, etc.)
    if bux_strlen(resp.extraHeaders) > 0 {
        bux_sb_append(sb, resp.extraHeaders);
    }

    // Content-Type
    if bux_strlen(resp.contentType) > 0 {
        bux_sb_append(sb, "Content-Type: ");
        bux_sb_append(sb, resp.contentType);
        bux_sb_append(sb, "\r\n");
    }

    // Content-Length
    let bodyLen: uint = bux_strlen(resp.body);
    bux_sb_append(sb, "Content-Length: ");
    bux_sb_append_int(sb, bodyLen as int64);
    bux_sb_append(sb, "\r\n");

    // Connection close
    bux_sb_append(sb, "Connection: close\r\n");

    bux_sb_append(sb, "\r\n");

    if bodyLen > 0 {
        bux_sb_append(sb, resp.body);
    }

    let result: String = bux_sb_build(sb);
    bux_sb_free(sb);
    return result;
}

// =============================================================================
// Parse query string: ?key=val&key2=val2 → key-value arrays
// =============================================================================
func Query_Parse(req: *Request, queryString: String) {
    if bux_strlen(queryString) == 0 { return; }
    let pairCount: uint = bux_str_split_count(queryString, "&");
    let cap: int = pairCount as int + 1;
    req.queryKeys = bux_alloc(cap as uint * 8) as *String;
    req.queryValues = bux_alloc(cap as uint * 8) as *String;
    req.queryCount = 0;

    var i: uint = 0;
    while i < pairCount {
        let pair: String = bux_str_split_part(queryString, "&", i);
        let eqPos: String = bux_strstr(pair, "=");
        var key: String = pair;
        var value: String = "";
        if String_Len(eqPos) > 0 {
            let keyLen: uint = String_Offset(eqPos, pair);
            key = bux_str_slice(pair, 0, keyLen);
            let valStart: uint = keyLen + 1;
            let pairLen: uint = bux_strlen(pair);
            if valStart < pairLen {
                value = bux_str_slice(pair, valStart, pairLen - valStart);
            }
        }
        req.queryKeys[req.queryCount] = key;
        req.queryValues[req.queryCount] = value;
        req.queryCount = req.queryCount + 1;
        i = i + 1;
    }
}

// =============================================================================
// Parse incoming HTTP request from raw bytes
// =============================================================================
func Request_Parse(raw: String) -> Request {
    var req: Request;
    req.method = HttpVerb { tag: HttpVerb_GET };
    req.path = "/";
    req.body = "";
    req.headerCount = 0;
    req.queryCount = 0;
    req.pathParamCount = 0;

    if String_Len(raw) == 0 { return req; }
    let rawLen: uint = bux_strlen(raw);
    if rawLen == 0 { return req; }

    // Find header/body boundary
    let boundary: String = bux_strstr(raw, "\r\n\r\n");
    var headerLen: uint = rawLen;
    if String_Len(boundary) > 0 {
        headerLen = String_Offset(boundary, raw);
        let bodyStart: uint = headerLen + 4;
        if bodyStart < rawLen {
            req.body = bux_str_slice(raw, bodyStart, rawLen - bodyStart);
        }
    }

    if headerLen == 0 { return req; }
    let headerBlock: String = bux_str_slice(raw, 0, headerLen);
    let lineCount: uint = bux_str_split_count(headerBlock, "\r\n");
    if lineCount == 0 { return req; }

    // Parse request line
    let requestLine: String = bux_str_split_part(headerBlock, "\r\n", 0);
    if bux_strlen(requestLine) > 0 {
        let methodStr: String = bux_str_split_part(requestLine, " ", 0);
        if String_Eq(methodStr, "GET")     { req.method = HttpVerb { tag: HttpVerb_GET }; }
        else if String_Eq(methodStr, "POST")    { req.method = HttpVerb { tag: HttpVerb_POST }; }
        else if String_Eq(methodStr, "PUT")     { req.method = HttpVerb { tag: HttpVerb_PUT }; }
        else if String_Eq(methodStr, "DELETE")  { req.method = HttpVerb { tag: HttpVerb_DELETE }; }

        let fullPath: String = bux_str_split_part(requestLine, " ", 1);
        // Split path and query string
        let qmark: String = bux_strstr(fullPath, "?");
        if String_Len(qmark) > 0 {
            let pathLen: uint = String_Offset(qmark, fullPath);
            req.path = bux_str_slice(fullPath, 0, pathLen);
            let qsStart: uint = pathLen + 1;
            let fullLen: uint = bux_strlen(fullPath);
            if qsStart < fullLen {
                let qs: String = bux_str_slice(fullPath, qsStart, fullLen - qsStart);
                Query_Parse(&req, qs);
            }
        } else {
            req.path = fullPath;
        }
    }

    // Parse headers
    let cap: int = lineCount as int + 1;
    req.headerKeys = bux_alloc(cap as uint * 8) as *String;
    req.headerValues = bux_alloc(cap as uint * 8) as *String;

    var i: uint = 1;
    while i < lineCount {
        let line: String = bux_str_split_part(headerBlock, "\r\n", i);
        let colonPos: String = bux_strstr(line, ": ");
        if String_Len(colonPos) > 0 {
            let keyLen: uint = String_Offset(colonPos, line);
            let key: String = bux_str_slice(line, 0, keyLen);
            let valStart: uint = keyLen + 2;
            let lineLen: uint = bux_strlen(line);
            var value: String = "";
            if valStart < lineLen {
                value = bux_str_slice(line, valStart, lineLen - valStart);
            }
            req.headerKeys[req.headerCount] = key;
            req.headerValues[req.headerCount] = value;
            req.headerCount = req.headerCount + 1;
        }
        i = i + 1;
    }

    return req;
}

// =============================================================================
// Path pattern matching: /users/{id} against /users/42 → extracts id=42
// =============================================================================
func Path_Match(pattern: String, path: String, req: *Request) -> bool {
    // Split both by "/"
    let patParts: uint = bux_str_split_count(pattern, "/");
    let pathParts: uint = bux_str_split_count(path, "/");

    if patParts != pathParts { return false; }

    // Count params to allocate
    var paramCount: int = 0;
    var pi: uint = 0;
    while pi < patParts {
        let patPart: String = bux_str_split_part(pattern, "/", pi);
        if String_StartsWith(patPart, "{") && String_Contains(patPart, "}") {
            paramCount = paramCount + 1;
        }
        pi = pi + 1;
    }

    let cap: int = paramCount + 1;
    req.pathParamKeys = bux_alloc(cap as uint * 8) as *String;
    req.pathParamValues = bux_alloc(cap as uint * 8) as *String;
    req.pathParamCount = 0;

    // Match and extract
    var i: uint = 0;
    while i < patParts {
        let patPart: String = bux_str_split_part(pattern, "/", i);
        let pathPart: String = bux_str_split_part(path, "/", i);

        if String_StartsWith(patPart, "{") && String_Contains(patPart, "}") {
            // Extract param name from {name}
            let braceOpen: uint = 1; // skip "{"
            let braceClose: String = bux_strstr(patPart, "}");
            var nameLen: uint = 0;
            if String_Len(braceClose) > 0 {
                nameLen = String_Offset(braceClose, patPart) - 1;
            }
            let name: String = bux_str_slice(patPart, braceOpen, nameLen);
            req.pathParamKeys[req.pathParamCount] = name;
            req.pathParamValues[req.pathParamCount] = pathPart;
            req.pathParamCount = req.pathParamCount + 1;
        } else {
            // Literal match
            if !String_Eq(patPart, pathPart) { return false; }
        }
        i = i + 1;
    }

    return true;
}

// =============================================================================
// App constructor
// =============================================================================
func App_New(port: int, threadCount: int) -> App {
    var app: App;
    app.port = port;
    app.threadCount = threadCount;
    app.serverName = "Boko/0.1.0 (Bux)";
    return app;
}

// =============================================================================
// Forward declaration — user must implement this in their module
// =============================================================================
func Boko_Router(req: Request) -> Response;

// =============================================================================
// Handle a single connection: parse → dispatch → respond
// =============================================================================
func App_HandleConnection(clientFd: int) {
    let raw: String = Net_Recv(clientFd, 8192);
    if String_Len(raw) == 0 { return; }
    if bux_strlen(raw) == 0 { return; }

    let req: Request = Request_Parse(raw);

    // Call user-defined dispatch (forward declaration — user must implement)
    let resp: Response = Boko_Router(req);

    // Log
    if req.method.tag == HttpVerb_GET    { Print("GET "); }
    else if req.method.tag == HttpVerb_POST   { Print("POST "); }
    else if req.method.tag == HttpVerb_PUT    { Print("PUT "); }
    else if req.method.tag == HttpVerb_DELETE { Print("DELETE "); }
    else { Print("? "); }
    Print(req.path);
    Print("  →  ");
    PrintInt(resp.statusCode);
    PrintLine("");

    // Send
    let respStr: String = Response_Build(resp);
    Net_Send(clientFd, respStr);
}

// =============================================================================
// Worker thread: accept loop
// =============================================================================
func App_Worker(serverFd: int) {
    while true {
        let clientFd: int = Net_Accept(serverFd);
        if clientFd < 0 { continue; }
        App_HandleConnection(clientFd);
        Net_Close(clientFd);
    }
}

// =============================================================================
// App_Run: start the server (blocking)
// =============================================================================
func App_Run(app: *App) {
    PrintLine("╔══════════════════════════════════════╗");
    PrintLine("║  Boko Framework v0.1.0               ║");
    PrintLine("║  Async web framework for Bux         ║");
    PrintLine("╚══════════════════════════════════════╝");
    PrintLine("");

    let fd: int = Net_Create();
    if fd < 0 {
        PrintLine("FATAL: socket() failed");
        return;
    }

    Net_SetReuse(fd);

    if !Net_Bind(fd, "0.0.0.0", app.port) {
        Print("FATAL: bind(:");
        PrintInt(app.port);
        Print(") failed: ");
        PrintLine(Net_LastError());
        Net_Close(fd);
        return;
    }

    if !Net_Listen(fd, 128) {
        PrintLine("FATAL: listen() failed");
        Net_Close(fd);
        return;
    }

    Print("✓ Boko running on http://0.0.0.0:");
    PrintInt(app.port);
    PrintLine("");
    Print("✓ Workers: ");
    PrintInt(app.threadCount);
    PrintLine("");
    PrintLine("");

    // Spawn workers
    var i: int = 0;
    while i < app.threadCount - 1 {
        spawn App_Worker(fd);
        i = i + 1;
    }

    // Main thread is the last worker
    App_Worker(fd);
}

} // module Boko