const std = @import("std");
const root = @import("root");
const builtin = @import("builtin");
const http = @import("http");
const api = @import("api");
const util = @import("util");
const query_utils = @import("./query.zig");
const json_utils = @import("./json.zig");

pub const auth = @import("./controllers/api/auth.zig");
pub const communities = @import("./controllers/api/communities.zig");
pub const invites = @import("./controllers/api/invites.zig");
pub const users = @import("./controllers/api/users.zig");
pub const follows = @import("./controllers/api/users/follows.zig");
pub const notes = @import("./controllers/api/notes.zig");
pub const streaming = @import("./controllers/api/streaming.zig");
pub const timelines = @import("./controllers/api/timelines.zig");

const web = @import("./controllers/web.zig");

const mdw = http.middleware;

const router = mdw.Router(&.{});

const not_found = struct {
    pub fn handler(
        _: @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 InjectApiConn(comptime ApiSource: type) type {
    return struct {
        api_source: ApiSource,
        fn getApiConn(self: @This(), alloc: std.mem.Allocator, req: anytype) !ApiSource.Conn {
            const host = req.headers.get("Host") orelse return error.NoHost;
            const auth_header = req.headers.get("Authorization");
            const token = if (auth_header) |header| blk: {
                const prefix = "bearer ";
                if (header.len < prefix.len) break :blk null;
                if (!std.ascii.eqlIgnoreCase(prefix, header[0..prefix.len])) break :blk null;
                break :blk header[prefix.len..];
            } else null;

            if (token) |t| return try self.api_source.connectToken(host, t, alloc);

            if (req.headers.getCookie("active_account") catch return error.BadRequest) |account| {
                if (account.len + ("token.").len <= 64) {
                    var buf: [64]u8 = undefined;
                    const cookie_name = std.fmt.bufPrint(&buf, "token.{s}", .{account}) catch unreachable;
                    if (try req.headers.getCookie(cookie_name)) |token_hdr| {
                        return try self.api_source.connectToken(host, token_hdr, alloc);
                    }
                } else return error.InvalidCookie;
            }

            return try self.api_source.connectUnauthorized(host, alloc);
        }

        fn handle(self: @This(), req: anytype, res: anytype, ctx: anytype, next: anytype) !void {
            var api_conn = try self.getApiConn(ctx.allocator, req);
            defer api_conn.close();

            return next.handle(
                req,
                res,
                mdw.injectContext(.{ .api_conn = &api_conn }),
                {},
            );
        }
    };
}

pub fn EndpointRequest(comptime Endpoint: type) type {
    return struct {
        pub const Args = if (@hasDecl(Endpoint, "Args")) Endpoint.Args else void;
        pub const Body = if (@hasDecl(Endpoint, "Body")) Endpoint.Body else void;
        pub const Query = if (@hasDecl(Endpoint, "Query")) Endpoint.Query else void;

        allocator: std.mem.Allocator,

        method: http.Method,
        uri: []const u8,
        headers: http.Fields,

        args: Args,
        body: Body,
        query: Query,

        const args_middleware = if (Args == void)
            mdw.injectContext(.{ .args = {} })
        else
            mdw.ParsePathArgs(Args){};

        const body_middleware = if (Body == void)
            mdw.injectContext(.{ .body = {} })
        else
            mdw.ParseBody(Body){};

        const query_middleware = if (Query == void)
            mdw.injectContext(.{ .query = {} })
        else
            mdw.ParseQueryParams(Query){};
    };
}

fn CallApiEndpoint(comptime Endpoint: type) type {
    return struct {
        fn handle(_: @This(), req: anytype, res: anytype, ctx: anytype, _: void) !void {
            const request = EndpointRequest(Endpoint){
                .allocator = ctx.allocator,

                .method = req.method,
                .uri = req.uri,
                .headers = req.headers,

                .args = ctx.args,
                .body = ctx.body,
                .query = ctx.query,
            };

            var response = Response{ .headers = http.Fields.init(ctx.allocator), .res = res };
            defer response.headers.deinit();

            return Endpoint.handler(request, &response, ctx.api_conn);
        }
    };
}

pub fn apiEndpoint(
    comptime Endpoint: type,
    api_source: anytype,
) return_type: {
    const RequestType = EndpointRequest(Endpoint);
    break :return_type mdw.Apply(std.meta.Tuple(.{
        mdw.Route,
        @TypeOf(RequestType.args_middleware),
        @TypeOf(RequestType.query_middleware),
        @TypeOf(RequestType.body_middleware),
        // TODO: allocation strategy
        InjectApiConn(@TypeOf(api_source)),
        CallApiEndpoint(Endpoint),
    }));
} {
    const RequestType = EndpointRequest(Endpoint);
    return mdw.apply(.{
        mdw.Route{ .desc = .{ .path = Endpoint.path, .method = Endpoint.method } },
        RequestType.args_middleware,
        RequestType.query_middleware,
        RequestType.body_middleware,
        // TODO: allocation strategy
        InjectApiConn(@TypeOf(api_source)){ .api_source = api_source },
        CallApiEndpoint(Endpoint){},
    });
}

pub fn routeRequest(api_source: anytype, req: *http.Request, res: *http.Response, alloc: std.mem.Allocator) void {
    // TODO: hashmaps?
    _ = .{ api_source, req, res, alloc };
    unreachable;
    //var response = Response{ .headers = http.Fields.init(alloc), .res = res };
    //defer response.headers.deinit();

    //const found = routeRequestInternal(api_source, req, &response, alloc);

    //if (!found) response.status(.not_found) catch {};
}

const routes = .{
    auth.login,
    auth.verify_login,
    communities.create,
    communities.query,
    invites.create,
    users.create,
    notes.create,
    notes.get,
    streaming.streaming,
    timelines.global,
    timelines.local,
    timelines.home,
    follows.create,
    follows.delete,
    follows.query_followers,
    follows.query_following,
} ++ web.routes;

pub const AllocationStrategy = enum {
    arena,
    normal,
};

pub const Response = struct {
    const Self = @This();
    headers: http.Fields,
    res: *http.Response,
    opened: bool = false,

    /// Write a response with no body, only a given status
    pub fn status(self: *Self, status_code: http.Status) !void {
        var stream = try self.open(status_code);
        defer stream.close();
        try stream.finish();
    }

    /// Write a request body as json
    pub fn json(self: *Self, status_code: http.Status, response_body: anytype) !void {
        try self.headers.put("Content-Type", "application/json");

        var stream = try self.open(status_code);
        defer stream.close();

        const writer = stream.writer();
        try std.json.stringify(response_body, json_options, writer);

        try stream.finish();
    }

    pub fn open(self: *Self, status_code: http.Status) !http.Response.ResponseStream {
        std.debug.assert(!self.opened);
        self.opened = true;

        return try self.res.open(status_code, &self.headers);
    }

    /// Prints the given error as json
    pub fn err(self: *Self, status_code: http.Status, message: []const u8, details: anytype) !void {
        return self.json(status_code, .{
            .message = message,
            .details = details,
        });
    }

    /// Signals that the HTTP connection should be hijacked without writing a
    /// response beforehand.
    pub fn hijack(self: *Self) *http.Response {
        std.debug.assert(!self.opened);
        self.opened = true;
        return self.res;
    }

    pub fn template(self: *Self, status_code: http.Status, comptime templ: []const u8, data: anytype) !void {
        try self.headers.put("Content-Type", "text/html");

        var stream = try self.open(status_code);
        defer stream.close();

        const writer = stream.writer();
        try @import("template").execute(writer, templ, data);

        try stream.finish();
    }
};

const json_options = if (builtin.mode == .Debug)
.{
    .whitespace = .{
        .indent = .{ .Space = 2 },
        .separator = true,
    },
    .string = .{ .String = .{} },
} else .{
    .whitespace = .{
        .indent = .None,
        .separator = false,
    },
    .string = .{ .String = .{} },
};

pub const helpers = struct {
    pub fn paginate(community: api.Community, path: []const u8, results: anytype, res: *Response, alloc: std.mem.Allocator) !void {
        var link = std.ArrayList(u8).init(alloc);
        const link_writer = link.writer();
        defer link.deinit();

        try writeLink(link_writer, community, path, results.next_page, "next");
        try link_writer.writeByte(',');
        try writeLink(link_writer, community, path, results.prev_page, "prev");

        try res.headers.put("Link", link.items);

        try res.json(.ok, results.items);
    }

    fn writeLink(
        writer: anytype,
        community: api.Community,
        path: []const u8,
        params: anytype,
        rel: []const u8,
    ) !void {
        // TODO: percent-encode
        try std.fmt.format(
            writer,
            "<{s}://{s}/{s}?",
            .{ @tagName(community.scheme), community.host, path },
        );

        try query_utils.formatQuery(params, writer);

        try std.fmt.format(
            writer,
            ">; rel=\"{s}\"",
            .{rel},
        );
    }
};