package com.example.aiapp

import java.io.IOException
import java.net.HttpURLConnection
import java.net.URL
import org.json.JSONArray
import org.json.JSONObject

// The REST half of the backend's surface (see server/src/routes.rs for the
// table); the SSE half is EventStream.kt. All blocking network calls --
// invoke from a background dispatcher. Each throws ApiException on failure,
// carrying the server's own explanation where it sent one, since those
// messages are written to be read on this screen.

// Shared with EventStream.kt, which connects the same way but then reads
// without a deadline.
const val CONNECT_TIMEOUT_MS = 5000
private const val READ_TIMEOUT_MS = 5000

class ApiException(message: String, cause: Throwable? = null) : Exception(message, cause)

/**
 * Runs one request against the backend, with the pinned TLS setup, the bearer token, and the
 * failure translation every call needs. [readBody] gets the connected, already-status-checked
 * connection to read from.
 *
 * @param readTimeoutMs how long to wait on the response body. The SSE stream doesn't come through
 *   here -- an event stream has no bounded read time (see EventStream.kt).
 */
fun <T> requestFromServer(
    settings: ServerSettings,
    path: String,
    method: String = "GET",
    jsonBody: String? = null,
    /** Raw request body as content-type to bytes -- the upload path. */
    binaryBody: Pair<String, ByteArray>? = null,
    readTimeoutMs: Int = READ_TIMEOUT_MS,
    readBody: (HttpURLConnection) -> T,
): T {
    val connection = URL("${settings.baseUrl}$path").openConnection() as HttpURLConnection
    try {
        connection.applyPinnedTls()
        connection.requestMethod = method
        connection.connectTimeout = CONNECT_TIMEOUT_MS
        connection.readTimeout = readTimeoutMs
        connection.setRequestProperty("Authorization", "Bearer ${settings.token}")
        if (jsonBody != null) {
            connection.doOutput = true
            connection.setRequestProperty("Content-Type", "application/json")
            connection.outputStream.use { it.write(jsonBody.encodeToByteArray()) }
        } else if (binaryBody != null) {
            connection.doOutput = true
            connection.setRequestProperty("Content-Type", binaryBody.first)
            connection.outputStream.use { it.write(binaryBody.second) }
        }
        if (connection.responseCode !in 200..299) {
            val detail = connection.errorStream?.bufferedReader()?.readText()?.trim()
            throw ApiException(
                when {
                    connection.responseCode == 401 ->
                        "The server rejected this device's token. Re-enroll by scanning " +
                            "the server's QR (or rotate with --rotate-token and scan the new one)."
                    detail.isNullOrEmpty() ->
                        "Server returned HTTP ${connection.responseCode} for $path"
                    else -> detail
                }
            )
        }
        return readBody(connection)
    } catch (e: ApiException) {
        throw e
    } catch (e: IOException) {
        // Surfacing the real exception (rather than one canned message for
        // every failure mode) is what lets this be diagnosed on a device
        // with no logcat access.
        throw ApiException(
            "Couldn't reach the server at ${settings.baseUrl} " +
                "(${e::class.simpleName}: ${e.message}) -- is ai-server running, and is " +
                "this device able to reach that address (WireGuard up)?",
            e,
        )
    } catch (e: Exception) {
        throw ApiException(
            "Reached ${settings.baseUrl}$path but couldn't read its response " +
                "(${e::class.simpleName}: ${e.message})",
            e,
        )
    } finally {
        connection.disconnect()
    }
}

/** The response body as one JSON object. */
private fun HttpURLConnection.jsonObject(): JSONObject =
    JSONObject(inputStream.bufferedReader().readText())

/** The response body as a JSON array of objects, each mapped through [parse]. */
private fun <T> HttpURLConnection.jsonObjects(parse: (JSONObject) -> T): List<T> =
    JSONArray(inputStream.bufferedReader().readText()).mapObjects(parse)

private fun <T> JSONArray.mapObjects(parse: (JSONObject) -> T): List<T> =
    (0 until length()).map { parse(getJSONObject(it)) }

private fun JSONArray.strings(): List<String> = (0 until length()).map { getString(it) }

/** Percent-encodes a value going into a query string. */
private fun String.urlEncoded(): String = java.net.URLEncoder.encode(this, Charsets.UTF_8.name())

// One row of GET /sessions. A session names the machine it runs on and
// which of that machine's providers it runs.
data class SessionSummary(
    val id: String,
    /**
     * The machine's current label. The id is deliberately not carried: nothing here addresses a
     * setup, and holding both invites showing the wrong one, which is what happened.
     */
    val setupName: String,
    val provider: String,
    val title: String,
    val model: String?,
    /** How much the session asks before acting; null when it was never set. */
    val permissionMode: String?,
    val status: String,
    val lastActivity: Double,
)

private fun parseSession(session: JSONObject) =
    SessionSummary(
        id = session.getString("id"),
        setupName = session.getString("setupName"),
        provider = session.getString("provider"),
        title = session.getString("title"),
        model = session.optString("model").ifEmpty { null },
        permissionMode = session.optString("permissionMode").ifEmpty { null },
        status = session.getString("status"),
        lastActivity = session.getDouble("lastActivity"),
    )

fun fetchSessions(settings: ServerSettings): List<SessionSummary> =
    requestFromServer(settings, "/sessions") { it.jsonObjects(::parseSession) }

// What the server offers, so the spawn screen has no hardcoded lists: a
// setup added to the server's config.ron appears here with no app rebuild.
//
// One list rather than two. A provider only exists on a machine that has
// it installed, so offering machines and providers as independent choices
// would offer pairs that cannot work.
data class Provider(val name: String, val kind: String, val models: List<String>)

/**
 * A machine, and what it can run. [address] is absent for the backend itself.
 *
 * [id] is stable and [name] is not: renaming a machine keeps its sessions, so everything that
 * refers to a setup uses the id and everything a person reads uses the name.
 */
data class Setup(
    val id: String,
    val name: String,
    val address: String?,
    val providers: List<Provider>,
)

private fun parseProvider(provider: JSONObject) =
    Provider(
        name = provider.getString("name"),
        kind = provider.getString("kind"),
        // Omitted entirely when the provider offers none.
        models = provider.optJSONArray("models")?.strings().orEmpty(),
    )

private fun parseSetup(setup: JSONObject) =
    Setup(
        id = setup.getString("id"),
        name = setup.getString("name"),
        address = setup.optString("address").ifEmpty { null },
        providers = setup.getJSONArray("providers").mapObjects(::parseProvider),
    )

fun fetchSetups(settings: ServerSettings): List<Setup> =
    requestFromServer(settings, "/setups") { it.jsonObjects(::parseSetup) }

/**
 * A Claude Code session already on a machine, which can be continued here.
 *
 * Identified by [id] and never by a path. The server resolves which file that is, so this app has
 * no way to ask it to read one -- the same rule that keeps a provider's command out of this client.
 */
data class Importable(
    val id: String,
    val cwd: String,
    val title: String,
    val modified: Double,
    val lines: Int,
    /** Whether [title] is a name somebody chose rather than the last thing said in the session. */
    val named: Boolean,
)

fun fetchImportable(settings: ServerSettings, setup: String): List<Importable> =
    requestFromServer(settings, "/setups/$setup/importable") {
        it.jsonObjects { session ->
            Importable(
                id = session.getString("id"),
                cwd = session.optString("cwd"),
                title = session.optString("title"),
                modified = session.optDouble("modified", 0.0),
                lines = session.optInt("lines", 0),
                named = session.optBoolean("named", false),
            )
        }
    }

/**
 * How to reach a machine. Deliberately carries no command: the server discovers what a machine can
 * run by asking it, so this app has no way to introduce something to run.
 *
 * [identityFile] is a path on the *backend*, not a key -- private keys do not travel.
 */
data class SshDetails(
    val address: String,
    val port: Int? = null,
    val identityFile: String? = null,
)

private fun SshDetails.toJson() =
    JSONObject().put("address", address).apply {
        if (port != null) put("port", port)
        if (!identityFile.isNullOrBlank()) put("identityFile", identityFile)
    }

/** What a machine turns out to have, without saving anything. */
fun probeSetup(settings: ServerSettings, ssh: SshDetails?): List<Provider> =
    requestFromServer(
        settings,
        "/setups/probe",
        method = "POST",
        jsonBody = JSONObject().apply { if (ssh != null) put("ssh", ssh.toJson()) }.toString(),
        readTimeoutMs = 40000,
    ) {
        it.jsonObjects(::parseProvider)
    }

fun addSetup(settings: ServerSettings, name: String, ssh: SshDetails?): Setup =
    requestFromServer(
        settings,
        "/setups",
        method = "POST",
        jsonBody =
            JSONObject()
                .put("name", name)
                .apply { if (ssh != null) put("ssh", ssh.toJson()) }
                .toString(),
        readTimeoutMs = 40000,
    ) {
        parseSetup(it.jsonObject())
    }

/** Renames a machine, and optionally asks it again what it has. */
fun updateSetup(
    settings: ServerSettings,
    id: String,
    name: String? = null,
    rediscover: Boolean = false,
): Setup =
    requestFromServer(
        settings,
        "/setups/${id.urlEncoded()}",
        method = "PUT",
        jsonBody =
            JSONObject()
                .apply {
                    if (name != null) put("name", name)
                    if (rediscover) put("rediscover", true)
                }
                .toString(),
        readTimeoutMs = 40000,
    ) {
        parseSetup(it.jsonObject())
    }

fun deleteSetup(settings: ServerSettings, id: String) {
    requestFromServer(settings, "/setups/${id.urlEncoded()}", method = "DELETE") {}
}

/**
 * Spawns a session and returns it as the list would show it. [setup] names the machine and
 * [provider] one of the things that machine offers.
 */
fun spawnSession(
    settings: ServerSettings,
    setup: String,
    provider: String,
    title: String,
    model: String? = null,
    cwd: String? = null,
    permissionMode: String? = null,
    params: Map<String, String> = emptyMap(),
    /** Continue this Claude Code session instead of starting an empty one. */
    import: String? = null,
): SessionSummary =
    requestFromServer(
        settings,
        "/sessions",
        method = "POST",
        jsonBody =
            JSONObject()
                .put("setup", setup)
                .put("provider", provider)
                .put("title", title)
                .apply {
                    if (!model.isNullOrBlank()) put("model", model)
                    if (!cwd.isNullOrBlank()) put("cwd", cwd)
                    if (!permissionMode.isNullOrBlank()) put("permissionMode", permissionMode)
                    if (!import.isNullOrBlank()) put("import", import)
                    if (params.isNotEmpty()) {
                        put("params", JSONObject(params.toMap<String, Any>()))
                    }
                }
                .toString(),
        readTimeoutMs = 30000,
    ) { connection ->
        parseSession(connection.jsonObject())
    }

fun sendMessage(
    settings: ServerSettings,
    sessionId: String,
    text: String,
    attachmentIds: List<String> = emptyList(),
) {
    requestFromServer(
        settings,
        "/sessions/$sessionId/message",
        method = "POST",
        jsonBody =
            JSONObject()
                .put("text", text)
                .put("attachmentIds", JSONArray(attachmentIds))
                .toString(),
    ) {}
}

/** Uploads one picked image; the returned id goes into [sendMessage]. */
fun uploadAttachment(
    settings: ServerSettings,
    sessionId: String,
    bytes: ByteArray,
    mime: String,
): String {
    val boundary = "----aiapp-${System.currentTimeMillis()}"
    val head =
        ("--$boundary\r\n" +
                "Content-Disposition: form-data; name=\"file\"; filename=\"image\"\r\n" +
                "Content-Type: $mime\r\n\r\n")
            .encodeToByteArray()
    val tail = "\r\n--$boundary--\r\n".encodeToByteArray()
    return requestFromServer(
        settings,
        "/sessions/$sessionId/attachments",
        method = "POST",
        binaryBody = "multipart/form-data; boundary=$boundary" to (head + bytes + tail),
        readTimeoutMs = 60000,
    ) { connection ->
        connection.jsonObject().getString("id")
    }
}

/** Fetches an image the transcript references (produced or uploaded). */
fun fetchSessionFile(settings: ServerSettings, sessionId: String, name: String): ByteArray =
    requestFromServer(settings, "/sessions/$sessionId/files/$name", readTimeoutMs = 30000) {
        it.inputStream.readBytes()
    }

// One rate-limit window, rendered as a labeled bar on the usage screen.
data class UsageWindow(
    val label: String,
    val percent: Double,
    val resetsAt: String?,
    val active: Boolean,
)

data class UsageSnapshot(
    val provider: String,
    val available: Boolean,
    val windows: List<UsageWindow>,
    val error: String?,
)

/** The backend caches; refreshing more often than its poll interval just re-reads the cache. */
fun fetchUsage(settings: ServerSettings): List<UsageSnapshot> =
    requestFromServer(settings, "/usage", readTimeoutMs = 30000) { connection ->
        connection.jsonObjects { snapshot ->
            UsageSnapshot(
                provider = snapshot.getString("provider"),
                available = snapshot.getBoolean("available"),
                error = snapshot.optString("error").ifEmpty { null },
                windows =
                    snapshot.getJSONArray("windows").mapObjects { window ->
                        UsageWindow(
                            label = window.getString("label"),
                            percent = window.getDouble("percent"),
                            resetsAt = window.optString("resetsAt").ifEmpty { null },
                            active = window.getBoolean("active"),
                        )
                    },
            )
        }
    }

fun answerQuestion(
    settings: ServerSettings,
    sessionId: String,
    questionId: String,
    answer: String,
) {
    requestFromServer(
        settings,
        "/sessions/$sessionId/answer",
        method = "POST",
        jsonBody = JSONObject().put("questionId", questionId).put("answer", answer).toString(),
    ) {}
}

fun interruptSession(settings: ServerSettings, sessionId: String) {
    requestFromServer(settings, "/sessions/$sessionId/interrupt", method = "POST") {}
}

/**
 * Removes a Claude Code session from the machine.
 *
 * The transcript *is* the session, so this ends any chance of resuming that conversation. The
 * caller confirms first; see ImportScreen.
 */
fun deleteImportable(settings: ServerSettings, setup: String, sessionId: String) {
    requestFromServer(settings, "/setups/$setup/importable/$sessionId", method = "DELETE") {}
}

/** Switches a running session's model; the CLI changes it in place. */
fun setSessionModel(settings: ServerSettings, sessionId: String, model: String) {
    requestFromServer(
        settings,
        "/sessions/$sessionId/model",
        method = "POST",
        jsonBody = JSONObject().put("model", model).toString(),
    ) {}
}

/** Switches how much a running session asks before acting, also in place. */
fun setSessionPermissionMode(settings: ServerSettings, sessionId: String, mode: String) {
    requestFromServer(
        settings,
        "/sessions/$sessionId/permission-mode",
        method = "POST",
        jsonBody = JSONObject().put("mode", mode).toString(),
    ) {}
}

fun deleteSession(settings: ServerSettings, sessionId: String) {
    requestFromServer(settings, "/sessions/$sessionId", method = "DELETE") {}
}

// Models: what this backend has downloaded, what it is downloading, and
// what HuggingFace offers. Browsing is proxied by the server rather than
// done here, because this app trusts exactly one certificate and has no
// general internet trust to spend on huggingface.co.

data class LocalModel(val key: String, val repo: String, val file: String, val bytes: Long)

/**
 * A download in flight or finished. [total] is null when the server never said how big the file is
 * -- which must render as "not known", never as a bar at some invented position.
 */
data class Download(
    val key: String,
    val run: Long,
    val repo: String,
    val file: String,
    val state: String,
    val done: Long,
    val total: Long?,
    val error: String?,
)

data class Models(val local: List<LocalModel>, val downloads: List<Download>)

data class RemoteRepo(val id: String, val downloads: Long, val likes: Long)

data class RemoteFile(val path: String, val bytes: Long, val have: Boolean)

private fun parseDownload(o: JSONObject) =
    Download(
        key = o.getString("key"),
        run = o.getLong("run"),
        repo = o.getString("repo"),
        file = o.getString("file"),
        state = o.getString("state"),
        done = o.getLong("done"),
        // Absent rather than zero when unknown; see the field's comment.
        total = if (o.has("total")) o.getLong("total") else null,
        error = if (o.has("error")) o.getString("error") else null,
    )

fun fetchModels(settings: ServerSettings): Models =
    requestFromServer(settings, "/models") { connection ->
        val body = JSONObject(connection.inputStream.bufferedReader().readText())
        Models(
            local =
                body.getJSONArray("local").mapObjects { m ->
                    LocalModel(
                        key = m.getString("key"),
                        repo = m.getString("repo"),
                        file = m.getString("file"),
                        bytes = m.getLong("bytes"),
                    )
                },
            downloads = body.getJSONArray("downloads").mapObjects(::parseDownload),
        )
    }

fun searchModels(settings: ServerSettings, query: String): List<RemoteRepo> =
    requestFromServer(settings, "/models/search?q=${query.urlEncoded()}") { connection ->
        connection.jsonObjects { r ->
            RemoteRepo(
                id = r.getString("id"),
                downloads = r.getLong("downloads"),
                likes = r.getLong("likes"),
            )
        }
    }

fun fetchRepoFiles(settings: ServerSettings, repo: String): List<RemoteFile> =
    requestFromServer(settings, "/models/files?repo=${repo.urlEncoded()}") { connection ->
        connection.jsonObjects { f ->
            RemoteFile(
                path = f.getString("path"),
                bytes = f.getLong("bytes"),
                have = f.getBoolean("have"),
            )
        }
    }

fun startDownload(settings: ServerSettings, repo: String, file: String): Download =
    requestFromServer(
        settings,
        "/models/download",
        method = "POST",
        jsonBody = JSONObject().put("repo", repo).put("file", file).toString(),
    ) { connection ->
        parseDownload(JSONObject(connection.inputStream.bufferedReader().readText()))
    }

fun cancelDownload(settings: ServerSettings, key: String) {
    requestFromServer(
        settings,
        "/models/cancel",
        method = "POST",
        jsonBody = JSONObject().put("key", key).toString(),
    ) {}
}

fun deleteModel(settings: ServerSettings, key: String) {
    requestFromServer(
        settings,
        "/models/delete",
        method = "POST",
        jsonBody = JSONObject().put("key", key).toString(),
    ) {}
}