const std = @import("std");
const zws = @import("zws");
const pq = @import("pq");
const mustache = @import("mustache");
const smtp = @import("smtp");

const Params = zws.Params;

const Err = error{
    Unexpected,
    AccessDenied,
    OutOfMemory,
    InputOutput,
    SystemResources,
    IsDir,
    OperationAborted,
    BrokenPipe,
    ConnectionResetByPeer,
    ConnectionTimedOut,
    NotOpenForReading,
    NetNameDeleted,
    WouldBlock,
    StreamTooLong,
    Malformatted,
    InvalidLength,
    InvalidCharacter,
    NoSpaceLeft,
    PqError,
    ColumnNotFound,
    DiskQuota,
    FileTooBig,
    DeviceBusy,
    InvalidArgument,
    NotOpenForWriting,
    LockViolation,
    InvalidRequestMethod,
};
const Ctx = struct {
    db: pq.Db,
    pub fn clone(self: @This()) Ctx {
        return Ctx{
            .db = self.db,
        };
    }
    pub fn deinit(self: @This()) void {
        _ = self;
    }
};

var gpa = std.heap.GeneralPurposeAllocator(.{}){};
const Request = struct {
    method: std.http.Method,
    target: []const u8,
};
const ResponseTransfer = union(enum) {
    content_length: u64,
    chunked: void,
    none: void,
};
const Headers = struct {
    const Entry = struct { key: []const u8, val: []const u8 };
    _internal: std.ArrayList(Entry),

    fn init(allocator: std.mem.Allocator) Headers {
        return .{ ._internal = std.ArrayList(Entry).init(allocator) };
    }
    fn append(self: *@This(), key: []const u8, val: []const u8) !void {
        try self._internal.append(.{ .key = key, .val = val });
    }
};
const Response = struct {
    allocator: std.mem.Allocator,
    request: Request,
    // TODO other fields and writer function to write headers and body to stdout
    status: std.http.Status,
    transfer_encoding: ResponseTransfer,
    headers: Headers,
    fn reader(_: @This()) std.fs.File.Reader {
        return std.io.getStdIn().reader();
    }
    fn do(self: @This()) !void {
        for (self.headers._internal.items) |tup| {
            try std.io.getStdOut().writeAll(tup.key);
            try std.io.getStdOut().writeAll(": ");
            try std.io.getStdOut().writeAll(tup.val);
            try std.io.getStdOut().writeAll("\r\n");
        }
        try std.io.getStdOut().writeAll("\r\n");
    }
    fn writer(_: @This()) std.fs.File.Writer {
        return std.io.getStdOut().writer();
    }
    fn finish(_: @This()) !void {
        // TODO Write empty lines? or just do nothing
    }
};

const Rtr = zws.Router(*Response, Ctx, Err);
const router = Rtr{
    .allocator = gpa.allocator(),
    .handlers = &[_]Rtr.Handler{
        .{
            .method = .GET,
            .pattern = "/api/comment",
            .handle_fn = get_comment,
        },
        .{
            .method = .POST,
            .pattern = "/api/comment",
            .handle_fn = post_comment,
        },
        .{
            .method = .GET,
            .pattern = "/api/form",
            .handle_fn = get_form,
        },
    },
    .notfound = notfound,
};

/// Run as a CGI program!
pub fn main() !void {
    const allocator = gpa.allocator();
    const db_url = std.os.getenv("DATABASE_URL") orelse "postgresql://comments@localhost/comments";
    var db = try pq.Db.init(db_url);
    // try db.exec(@embedFile("migrations/0_init.sql"));
    // try db.exec(@embedFile("migrations/1_capcha.sql"));
    defer db.deinit();
    const req = Request{
        .method = std.meta.stringToEnum(std.http.Method, std.os.getenv("REQUEST_METHOD") orelse "GET") orelse {
            return error.InvalidRequestMethod;
        },
        .target = std.os.getenv("REQUEST_URI") orelse "/",
    };
    var res = Response{
        .allocator = allocator,
        .request = req,
        .status = .bad_request,
        .transfer_encoding = .none,
        .headers = Headers.init(allocator),
    };
    const ctx = Ctx{ .db = db };
    try router.handle(&res, ctx);
}

fn notfound(res: *Response, _: Ctx) Err!void {
    const rr = @embedFile("templates/notfound.html");
    try constresponse(res, rr, .not_found);
}

fn badrequest(res: *Response, _: Ctx) Err!void {
    const rr = @embedFile("templates/badrequest.html");
    try constresponse(res, rr, .bad_request);
}

fn constresponse(res: *Response, rr: []const u8, status: std.http.Status) Err!void {
    res.status = status;
    res.transfer_encoding = .{ .content_length = rr.len };
    try res.headers.append("content-type", "text/html");
    try res.do();
    try res.writer().writeAll(rr);
    try res.finish();
}

fn get_comment(res: *Response, ctx: Ctx, _: Params) Err!void {
    var p = try zws.Path.parse(res.allocator, res.request.target);
    defer p.deinit();
    const url: []const u8 = try p.get_query_param("url") orelse {
        try badrequest(res, ctx);
        return;
    };

    const Comment = struct {
        author: []const u8,
        comment: []const u8,
        ts: []const u8,
    };
    var comments = std.ArrayList(Comment).init(res.allocator);
    var stmt = try ctx.db.prepare_statement(res.allocator,
        \\ select author,comment,ts from comments where url = $1 order by ts
    );
    defer stmt.deinit();
    try stmt.bind(0, url);
    while (try stmt.step()) {
        const cmt = try stmt.read_struct(Comment);
        try comments.append(cmt);
    }

    const rr = @embedFile("templates/comments.html");
    const tt = comptime mustache.parseComptime(rr, .{}, .{});
    res.transfer_encoding = .chunked;
    try res.headers.append("content-type", "text/html");
    try res.do();

    const data = struct {
        comments: []const Comment,
    };
    try mustache.render(tt, data{
        .comments = comments.items,
    }, res.writer());
    try res.finish();
}

fn post_comment(res: *Response, ctx: Ctx, _: Params) Err!void {
    var body_aa = std.ArrayList(u8).init(res.allocator);
    try res.reader().readAllArrayList(&body_aa, 1_000_000);
    var body = try body_aa.toOwnedSlice();
    var form = try zws.Form.parse(res.allocator, body);
    const Form = struct {
        url: []const u8,
        capcha_id: []const u8,
        author: []const u8,
        comment: []const u8,
        capcha_answer: []const u8,
    };
    const form_val = form.form_to_struct(Form) catch {
        try badrequest(res, ctx);
        return;
    };

    // Validate the capcha
    {
        var stmt = try ctx.db.prepare_statement(res.allocator, "select answer from capchas where id = $1");
        defer stmt.deinit();
        try stmt.bind(0, form_val.capcha_id);
        if (!try stmt.step()) {
            std.log.err("missing capcha_id {s}", .{form_val.capcha_id});
            try badrequest(res, ctx);
            return;
        }
        const ans = try stmt.read_column(0, []const u8);
        if (!std.mem.eql(u8, ans, form_val.capcha_answer)) {
            try constresponse(res, @embedFile("templates/capchainvalid.html"), std.http.Status.unauthorized);
            return;
        }
    }

    // Add the comment...
    {
        var stmt = try ctx.db.prepare_statement(res.allocator, "insert into comments(url,author,comment) values($1, $2, $3)");
        defer stmt.deinit();
        try stmt.bind(0, form_val.url);
        try stmt.bind(1, form_val.author);
        try stmt.bind(2, form_val.comment);
        _ = try stmt.step();
    }

    // Send me an email
    const rr = @embedFile("templates/notification.txt");
    const tt = comptime mustache.parseComptime(rr, .{}, .{});
    const Data = struct { url: []const u8, author: []const u8, comment: []const u8 };
    const notification = try mustache.allocRender(res.allocator, tt, Data{
        .url = form_val.url,
        .author = form_val.author,
        .comment = form_val.comment,
    });
    const smtp_username = std.os.getenv("SMTP_USERNAME") orelse "comments@mfashby.net";
    const smtp_password = std.os.getenv("SMTP_PASSWORD") orelse "foobar";
    const notification_address = std.os.getenv("NOTIFICATION_ADDRESS") orelse "martin@mfashby.net";
    const smtp_server = std.os.getenv("SMTP_SERVER") orelse "mail.mfashby.net:587";
    smtp.send_mail(res.allocator, smtp_server, .{ .user = smtp_username, .pass = smtp_password }, smtp_username, &[_][]const u8{notification_address}, notification) catch |err| {
        std.log.err("failed to send notification email {}", .{err});
    };

    // And redirect!
    res.transfer_encoding = .none;
    res.status = .found;
    try res.headers.append("location", form_val.url);
    try res.do();
    try res.finish();
}

fn get_form(res: *Response, ctx: Ctx, _: Params) Err!void {
    var p = try zws.Path.parse(res.allocator, res.request.target);
    defer p.deinit();
    const url: []const u8 = try p.get_query_param("url") orelse {
        try badrequest(res, ctx);
        return;
    };

    var stmt = try ctx.db.prepare_statement(res.allocator, "select id, question from capchas order by random() limit 1");
    defer stmt.deinit();
    if (!try stmt.step()) {
        std.log.err("no capcha!", .{});
        try badrequest(res, ctx);
        return;
    }
    const Capcha = struct {
        id: []const u8,
        question: []const u8,
    };
    const capcha = try stmt.read_struct(Capcha);

    const rr = @embedFile("templates/form.html");
    const tt = comptime mustache.parseComptime(rr, .{}, .{});

    res.transfer_encoding = .chunked;
    try res.headers.append("content-type", "text/html");
    try res.do();
    // For some reason, mustache.render won't work with anonymous struct
    const data = struct {
        capcha_id: []const u8,
        capcha_question: []const u8,
        url: []const u8,
    };
    try mustache.render(tt, data{
        .capcha_id = capcha.id,
        .capcha_question = capcha.question,
        .url = url,
    }, res.writer());
    try res.finish();
}