wttr/src/location/resolver.zig

const std = @import("std");
const GeoIp = @import("GeoIp.zig");
const GeoCache = @import("GeoCache.zig");
const Airports = @import("Airports.zig");
const Coordinates = @import("../Coordinates.zig");

pub const Location = struct {
    name: []const u8,
    coords: Coordinates,
};

pub const LocationType = enum {
    city_name,
    airport_code,
    special_location,
    ip_address,
    domain_name,
};

pub const Resolver = struct {
    allocator: std.mem.Allocator,
    geoip: ?*GeoIp,
    geocache: *GeoCache,
    airports: ?*Airports,

    pub fn init(allocator: std.mem.Allocator, geoip: ?*GeoIp, geocache: *GeoCache, airports: ?*Airports) Resolver {
        return .{
            .allocator = allocator,
            .geoip = geoip,
            .geocache = geocache,
            .airports = airports,
        };
    }

    pub fn resolve(self: *Resolver, query: []const u8) !Location {
        const location_type = detectType(query);

        return switch (location_type) {
            .ip_address => try self.resolveIP(query),
            .domain_name => try self.resolveDomain(query[1..]), // Skip '@'
            .special_location => try self.resolveGeocoded(query[1..]), // Skip '~'
            .airport_code => try self.resolveAirport(query),
            .city_name => try self.resolveGeocoded(query),
        };
    }

    fn detectType(query: []const u8) LocationType {
        if (query.len == 0) return .city_name;
        if (query[0] == '@') return .domain_name;
        if (query[0] == '~') return .special_location;
        if (query.len == 3 and isAlpha(query)) return .airport_code;
        if (isIPAddress(query)) return .ip_address;
        return .city_name;
    }

    fn resolveIP(self: *Resolver, ip: []const u8) !Location {
        if (self.geoip) |geoip| {
            if (try geoip.lookup(ip)) |coords| {
                return .{
                    .name = try self.allocator.dupe(u8, ip),
                    .coords = coords,
                };
            }
        }
        return error.LocationNotFound;
    }

    fn resolveDomain(self: *Resolver, domain: []const u8) !Location {
        // Use std.net to resolve domain to IP
        const addr_list = std.net.getAddressList(self.allocator, domain, 0) catch {
            return error.LocationNotFound;
        };
        defer addr_list.deinit();

        if (addr_list.addrs.len == 0) {
            return error.LocationNotFound;
        }

        // Format IP address
        const ip_str = try std.fmt.allocPrint(self.allocator, "{any}", .{addr_list.addrs[0].any});
        defer self.allocator.free(ip_str);

        return self.resolveIP(ip_str);
    }

    fn resolveGeocoded(self: *Resolver, name: []const u8) !Location {
        // Check cache first
        if (self.geocache.get(name)) |cached| {
            return Location{
                .name = try self.allocator.dupe(u8, cached.name),
                .coords = cached.coords,
            };
        }

        // Call Nominatim API
        const url = try std.fmt.allocPrint(
            self.allocator,
            "https://nominatim.openstreetmap.org/search?q={s}&format=json&limit=1",
            .{name},
        );
        defer self.allocator.free(url);

        var client = std.http.Client{ .allocator = self.allocator };
        defer client.deinit();

        const uri = try std.Uri.parse(url);

        var response_buf: [1024 * 1024]u8 = undefined;
        var writer = std.Io.Writer.fixed(&response_buf);
        const result = client.fetch(.{
            .location = .{ .uri = uri },
            .method = .GET,
            .response_writer = &writer,
            .extra_headers = &.{
                .{ .name = "User-Agent", .value = "wttr.in-zig/1.0" },
            },
        }) catch {
            std.log.warn("Nominatim API call failed for: {s}", .{name});
            return error.GeocodingFailed;
        };

        if (result.status != .ok) {
            return error.GeocodingFailed;
        }

        const response_body = response_buf[0..writer.end];

        // Parse JSON response
        const parsed = try std.json.parseFromSlice(
            std.json.Value,
            self.allocator,
            response_body,
            .{},
        );
        defer parsed.deinit();

        if (parsed.value.array.items.len == 0) {
            return error.LocationNotFound;
        }

        const first = parsed.value.array.items[0];
        const display_name = first.object.get("display_name").?.string;
        const lat = try std.fmt.parseFloat(f64, first.object.get("lat").?.string);
        const lon = try std.fmt.parseFloat(f64, first.object.get("lon").?.string);

        // Cache the result
        try self.geocache.put(name, .{
            .name = display_name,
            .coords = .{
                .latitude = lat,
                .longitude = lon,
            },
        });

        return Location{
            .name = try self.allocator.dupe(u8, display_name),
            .coords = .{
                .latitude = lat,
                .longitude = lon,
            },
        };
    }

    fn resolveAirport(self: *Resolver, code: []const u8) !Location {
        // Try airport database first
        if (self.airports) |airports| {
            // Convert to uppercase for lookup
            var upper_code: [3]u8 = undefined;
            for (code, 0..) |c, i| {
                upper_code[i] = std.ascii.toUpper(c);
            }

            if (airports.lookup(&upper_code)) |airport| {
                return Location{
                    .name = try self.allocator.dupe(u8, airport.name),
                    .coords = airport.coords,
                };
            }
        }

        // Fall back to geocoding
        return self.resolveGeocoded(code);
    }

    fn isAlpha(s: []const u8) bool {
        for (s) |c| {
            if (!std.ascii.isAlphabetic(c)) return false;
        }
        return true;
    }

    fn isIPAddress(s: []const u8) bool {
        // Simple check for IPv4
        var dots: u8 = 0;
        for (s) |c| {
            if (c == '.') {
                dots += 1;
            } else if (!std.ascii.isDigit(c)) {
                return false;
            }
        }
        return dots == 3;
    }
};

test "detect IP address" {
    try std.testing.expect(Resolver.isIPAddress("192.168.1.1"));
    try std.testing.expect(!Resolver.isIPAddress("not.an.ip"));
}

test "detect location type" {
    try std.testing.expectEqual(LocationType.ip_address, Resolver.detectType("8.8.8.8"));
    try std.testing.expectEqual(LocationType.domain_name, Resolver.detectType("@github.com"));
    try std.testing.expectEqual(LocationType.special_location, Resolver.detectType("~Eiffel+Tower"));
    try std.testing.expectEqual(LocationType.airport_code, Resolver.detectType("muc"));
    try std.testing.expectEqual(LocationType.city_name, Resolver.detectType("London"));
}

test "resolver init" {
    const allocator = std.testing.allocator;
    var geocache = try GeoCache.init(allocator, null);
    defer geocache.deinit();
    const resolver = Resolver.init(allocator, null, &geocache, null);
    try std.testing.expect(resolver.geoip == null);
    try std.testing.expect(resolver.airports == null);
}