From 73f7022d3602c512284e75d35b6e8dc549ca79c3 Mon Sep 17 00:00:00 2001
From: jaina heartles <me@heartles.xyz>
Date: Wed, 23 Nov 2022 20:51:30 -0800
Subject: [PATCH] Start work on middleware api

---
 src/http/lib.zig         |   2 +
 src/http/middleware.zig  | 345 +++++++++++++++++++++++++++++++++++++++
 src/main/controllers.zig |  30 +++-
 src/util/iters.zig       |  25 ++-
 4 files changed, 391 insertions(+), 11 deletions(-)
 create mode 100644 src/http/middleware.zig

diff --git a/src/http/lib.zig b/src/http/lib.zig
index 26f7756..9a4d8c9 100644
--- a/src/http/lib.zig
+++ b/src/http/lib.zig
@@ -15,6 +15,8 @@ pub const Response = server.Response;
 pub const Handler = server.Handler;
 pub const Server = server.Server;
 
+pub const middleware = @import("./middleware.zig");
+
 pub const Fields = @import("./headers.zig").Fields;
 
 pub const Protocol = enum {
diff --git a/src/http/middleware.zig b/src/http/middleware.zig
new file mode 100644
index 0000000..428d52f
--- /dev/null
+++ b/src/http/middleware.zig
@@ -0,0 +1,345 @@
+const std = @import("std");
+const root = @import("root");
+const builtin = @import("builtin");
+const http = @import("./lib.zig");
+const util = @import("util");
+//const query_utils = @import("./query.zig");
+//const json_utils = @import("./json.zig");
+const json_utils = util;
+const query_utils = util;
+
+fn AddFields(comptime lhs: type, comptime rhs: type) type {
+    const Ctx = @Type(.{ .Struct = .{
+        .layout = .Auto,
+        .fields = std.meta.fields(lhs) ++ std.meta.fields(rhs),
+        .decls = &.{},
+        .is_tuple = false,
+    } });
+    return Ctx;
+}
+
+fn addFields(lhs: anytype, rhs: anytype) AddFields(@TypeOf(lhs), @TypeOf(rhs)) {
+    var result: AddFields(@TypeOf(lhs), @TypeOf(rhs)) = undefined;
+    inline for (comptime std.meta.fieldNames(@TypeOf(lhs))) |f| @field(result, f) = @field(lhs, f);
+    inline for (comptime std.meta.fieldNames(@TypeOf(rhs))) |f| @field(result, f) = @field(rhs, f);
+    return result;
+}
+
+test {
+    // apply is a plumbing function that applies a tuple of middlewares in order
+    const base = apply(.{
+        split_uri,
+        mount("/abc"),
+    });
+
+    const request = .{ .uri = "/abc/defg/hijkl?some_query=true#section" };
+    const response = .{};
+    const initial_context = .{};
+    try base.handle(request, response, initial_context, {});
+}
+
+fn ApplyInternal(comptime fields: []const std.builtin.Type.StructField) type {
+    if (fields.len == 0) return void;
+
+    return NextHandler(
+        fields[0].field_type,
+        ApplyInternal(fields[1..]),
+    );
+}
+
+fn applyInternal(middlewares: anytype, comptime fields: []const std.builtin.Type.StructField) ApplyInternal(fields) {
+    if (fields.len == 0) return {};
+    return .{
+        .first = @field(middlewares, fields[0].name),
+        .next = applyInternal(middlewares, fields[1..]),
+    };
+}
+
+pub fn apply(middlewares: anytype) ApplyInternal(std.meta.fields(@TypeOf(middlewares))) {
+    return applyInternal(middlewares, std.meta.fields(@TypeOf(middlewares)));
+}
+
+pub fn AddContext(comptime Rhs: type) type {
+    return struct {
+        values: Rhs,
+        pub fn handle(self: @This(), req: anytype, res: anytype, ctx: anytype, next: anytype) !void {
+            return next.handle(req, res, addFields(ctx, self.values), {});
+        }
+    };
+}
+
+pub fn NextHandler(comptime First: type, comptime Next: type) type {
+    return struct {
+        first: First,
+        next: Next,
+
+        pub fn handle(
+            self: @This(),
+            req: anytype,
+            res: anytype,
+            ctx: anytype,
+            next: void,
+        ) !void {
+            _ = next;
+            return self.first.handle(req, res, ctx, self.next);
+        }
+    };
+}
+
+pub fn CatchErrors(comptime ErrorHandler: type) type {
+    return struct {
+        error_handler: ErrorHandler,
+        pub fn handle(self: @This(), req: anytype, res: anytype, ctx: anytype, next: anytype) !void {
+            return next.handle(req, res, ctx, {}) catch |err| {
+                return self.error_handler.handle(
+                    req,
+                    res,
+                    addFields(ctx, .{ .err = err }),
+                    next,
+                );
+            };
+        }
+    };
+}
+pub fn catchErrors(error_handler: anytype) CatchErrors(@TypeOf(error_handler)) {
+    return .{ .error_handler = error_handler };
+}
+
+pub const default_error_handler = struct {
+    fn handle(_: @This(), req: anytype, res: anytype, ctx: anytype, next: anytype) !void {
+        _ = next;
+        std.log.err("Error {} on uri {s}", .{ ctx.err, req.uri });
+        if (!res.was_opened) {
+            if (res.open(.internal_server_error)) |stream| {
+                defer stream.close();
+                stream.finish() catch {};
+            }
+        }
+
+        // Tell the server to close the connection after this request
+        res.should_close = true;
+    }
+}{};
+
+pub const split_uri = struct {
+    pub fn handle(_: @This(), req: anytype, res: anytype, ctx: anytype, next: anytype) !void {
+        var frag_split = std.mem.split(u8, req.uri, "#");
+        const without_fragment = frag_split.first();
+        const fragment = frag_split.rest();
+
+        var query_split = std.mem.split(u8, without_fragment, "?");
+        const path = query_split.first();
+        const query = query_split.rest();
+
+        const added_ctx = .{
+            .path = path,
+            .query_string = query,
+            .fragment_string = fragment,
+        };
+
+        return next.handle(
+            req,
+            res,
+            addFields(ctx, added_ctx),
+            {},
+        );
+    }
+}{};
+
+// helper function for doing route analysis
+fn routeApplies(comptime R: type, req: anytype) bool {
+    if (R.method != req.method) return false;
+
+    var path_iter = util.PathIter.from(req.path);
+    comptime var route_iter = util.PathIter.from(R.path);
+    inline while (comptime route_iter.next()) |route_segment| {
+        const path_segment = path_iter.next() orelse return false;
+        if (route_segment.len > 0 and route_segment[0] == ':') {
+            // Route Argument
+        } else {
+            if (!std.ascii.eqlIgnoreCase(route_segment, path_segment)) return false;
+        }
+    }
+    if (path_iter.next() != null) return false;
+
+    return true;
+}
+
+// routes a request to the correct handler based on declared HTTP method and path
+pub fn Router(comptime Routes: []const type) type {
+    return struct {
+        routes: std.meta.Tuple(Routes),
+
+        pub fn handle(self: @This(), req: anytype, res: anytype, ctx: anytype, next: void) !void {
+            _ = next;
+
+            inline for (self.routes) |r| if (routeApplies(@TypeOf(r), req, ctx)) {
+                if (r.handle(req, res, ctx, {})) |_| {
+                    // success!
+                    return;
+                } else |err| switch (err) {
+                    error.RouteMismatch => {},
+                    else => return err,
+                }
+            };
+
+            return error.RouteMismatch;
+        }
+    };
+}
+
+pub fn Mount(comptime route: []const u8) type {
+    return struct {
+        pub fn handle(_: @This(), req: anytype, res: anytype, ctx: anytype, next: anytype) !void {
+            var path_iter = util.PathIter.from(ctx.path);
+            comptime var route_iter = util.PathIter.from(route);
+            var path_unused = ctx.path;
+
+            inline while (comptime route_iter.next()) |route_segment| {
+                if (comptime route_segment.len == 0) continue;
+                const path_segment = path_iter.next() orelse return error.RouteMismatch;
+                path_unused = path_iter.rest();
+                if (comptime route_segment[0] == ':') {
+                    @compileLog("Argument segments cannot be mounted");
+                    // Route Argument
+                } else {
+                    if (!std.ascii.eqlIgnoreCase(route_segment, path_segment)) return error.RouteMismatch;
+                }
+            }
+
+            var new_ctx = ctx;
+            new_ctx.path = path_unused;
+            return next.handle(req, res, new_ctx, {});
+        }
+    };
+}
+pub fn mount(comptime route: []const u8) Mount(route) {
+    return .{};
+}
+
+pub fn HandleNotFound(comptime NotFoundHandler: type) type {
+    return struct {
+        not_found: NotFoundHandler,
+
+        pub fn handler(self: @This(), req: anytype, res: anytype, ctx: anytype, next: anytype) !void {
+            return next.handler(req, res, ctx, {}) catch |err| switch (err) {
+                error.RouteMismatch => return self.not_found.handler(req, res, ctx, {}),
+                else => return err,
+            };
+        }
+    };
+}
+
+fn parsePathArgs(comptime route: []const u8, comptime Args: type, path: []const u8) !Args {
+    var args: Args = undefined;
+    var path_iter = util.PathIter.from(path);
+    comptime var route_iter = util.PathIter.from(route);
+    inline while (comptime route_iter.next()) |route_segment| {
+        const path_segment = path_iter.next() orelse return error.RouteMismatch;
+        if (route_segment.len > 0 and route_segment[0] == ':') {
+            // route segment is an argument segment
+            const A = @TypeOf(@field(args, route_segment[1..]));
+            @field(args, route_segment[1..]) = try parsePathArg(A, path_segment);
+        } else {
+            if (!std.ascii.eqlIgnoreCase(route_segment, path_segment)) return error.RouteMismatch;
+        }
+    }
+
+    if (path_iter.next() != null) return error.RouteMismatch;
+
+    return args;
+}
+
+fn parsePathArg(comptime T: type, segment: []const u8) !T {
+    if (T == []const u8) return segment;
+    if (comptime std.meta.trait.isContainer(T) and std.meta.trait.hasFn("parse")(T)) return T.parse(segment);
+
+    @compileError("Unsupported Type " ++ @typeName(T));
+}
+
+pub fn ParsePathArgs(comptime route: []const u8, comptime Args: type) type {
+    return struct {
+        pub fn handle(_: @This(), req: anytype, res: anytype, ctx: anytype, next: anytype) !void {
+            return next.handle(
+                req,
+                res,
+                addFields(ctx, .{ .args = parsePathArgs(route, Args, req.path) }),
+                {},
+            );
+        }
+    };
+}
+
+const BaseContentType = enum {
+    json,
+    url_encoded,
+    octet_stream,
+
+    other,
+};
+
+fn parseBody(comptime T: type, content_type: BaseContentType, reader: anytype, alloc: std.mem.Allocator) !T {
+    const buf = try reader.readAllAlloc(alloc, 1 << 16);
+    defer alloc.free(buf);
+
+    switch (content_type) {
+        .octet_stream, .json => {
+            const body = try json_utils.parse(T, buf, alloc);
+            defer json_utils.parseFree(body, alloc);
+
+            return try util.deepClone(alloc, body);
+        },
+        .url_encoded => return query_utils.parseQuery(alloc, T, buf) catch |err| switch (err) {
+            error.NoQuery => error.NoBody,
+            else => err,
+        },
+        else => return error.UnsupportedMediaType,
+    }
+}
+
+fn matchContentType(hdr: ?[]const u8) ?BaseContentType {
+    if (hdr) |h| {
+        if (std.ascii.eqlIgnoreCase(h, "application/x-www-form-urlencoded")) return .url_encoded;
+        if (std.ascii.eqlIgnoreCase(h, "application/json")) return .json;
+        if (std.ascii.eqlIgnoreCase(h, "application/octet-stream")) return .octet_stream;
+
+        return .other;
+    }
+
+    return null;
+}
+
+pub fn ParseBody(comptime Body: type) type {
+    return struct {
+        pub fn handle(_: @This(), req: anytype, res: anytype, ctx: anytype, next: anytype) !void {
+            const base_content_type = matchContentType(req.headers.get("Content-Type"));
+
+            var stream = req.body orelse return error.NoBody;
+            const body = try parseBody(Body, base_content_type orelse .json, stream.reader(), ctx.allocator);
+            defer ctx.allocator.free(body);
+
+            return next.handler(
+                req,
+                res,
+                addFields(ctx, .{ .body = body }),
+            );
+        }
+    };
+}
+
+pub fn ParseQueryParams(comptime Next: type, comptime QueryParams: type) type {
+    return struct {
+        next: Next,
+
+        pub fn handler(self: @This(), req: anytype, res: anytype, ctx: anytype) !void {
+            const query = try query_utils.parseQuery(ctx.allocator, QueryParams, ctx.query_string);
+            defer ctx.allocator.free(query);
+
+            return self.next.handler(
+                req,
+                res,
+                addFields(ctx, .{ .query = query }),
+            );
+        }
+    };
+}
diff --git a/src/main/controllers.zig b/src/main/controllers.zig
index 007e909..3c22e66 100644
--- a/src/main/controllers.zig
+++ b/src/main/controllers.zig
@@ -18,14 +18,36 @@ pub const timelines = @import("./controllers/api/timelines.zig");
 
 const web = @import("./controllers/web.zig");
 
+const mdw = http.middleware;
+
+const router = Router(&.{});
+
+const not_found = struct {
+    pub fn handler(self: @This(), _: anytype, res: anytype, ctx: anytype) !void {
+        var headers = http.Fields.init(ctx.allocator);
+        defer headers.deinit();
+
+        var stream = try res.open(.not_found, &headers);
+        defer stream.close();
+        try stream.finish();
+    }
+};
+
+const base_handler = mdw.SplitUri(mdw.CatchErrors(not_found, mdw.DefaultErrorHandler));
+
+fn ApiCall(comptime Route: type) type {
+    return mdw.
+}
+
 pub fn routeRequest(api_source: anytype, req: *http.Request, res: *http.Response, alloc: std.mem.Allocator) void {
     // TODO: hashmaps?
-    var response = Response{ .headers = http.Fields.init(alloc), .res = res };
-    defer response.headers.deinit();
+    base_handler
+    //var response = Response{ .headers = http.Fields.init(alloc), .res = res };
+    //defer response.headers.deinit();
 
-    const found = routeRequestInternal(api_source, req, &response, alloc);
+    //const found = routeRequestInternal(api_source, req, &response, alloc);
 
-    if (!found) response.status(.not_found) catch {};
+    //if (!found) response.status(.not_found) catch {};
 }
 
 fn routeRequestInternal(api_source: anytype, req: *http.Request, res: *Response, alloc: std.mem.Allocator) bool {
diff --git a/src/util/iters.zig b/src/util/iters.zig
index b19c5bd..5ad2258 100644
--- a/src/util/iters.zig
+++ b/src/util/iters.zig
@@ -49,19 +49,30 @@ pub const QueryIter = struct {
 
 pub const PathIter = struct {
     is_first: bool,
-    iter: Separator('/'),
+    iter: std.mem.SplitIterator(u8),
 
     pub fn from(path: []const u8) PathIter {
-        return .{ .is_first = true, .iter = Separator('/').from(path) };
+        return .{ .is_first = true, .iter = std.mem.split(u8, path, "/") };
     }
 
     pub fn next(self: *PathIter) ?[]const u8 {
-        if (self.is_first) {
-            self.is_first = false;
-            return self.iter.next() orelse "";
-        }
+        defer self.is_first = false;
+        while (self.iter.next()) |it| if (it.len != 0) {
+            return it;
+        };
 
-        return self.iter.next();
+        if (self.is_first) return self.iter.rest();
+
+        return null;
+    }
+
+    pub fn first(self: *PathIter) []const u8 {
+        std.debug.assert(self.is_first);
+        return self.next().?;
+    }
+
+    pub fn rest(self: *PathIter) []const u8 {
+        return self.iter.rest();
     }
 };