#pragma once

#include <cstdint>
#include <filesystem>
#include <optional>
#include <string>
#include <unordered_map>
#include <vector>

#include "engine/framework/core/backend.h"

#include "frontend.h"
#include "http.h"

namespace minitts::server {

constexpr uint64_t kDefaultMaxRequestBodyBytes = 2ull * 1024ull * 1024ull * 1024ull;

// Per-model overrides of the server-level `live_ingest` block. Each field is
// independently optional: a model that only needs a longer deadline says so and
// inherits the rest, rather than restating the whole policy and drifting from it.
struct LiveIngestOverrides {
    std::optional<int> idle_timeout_ms;
    std::optional<int> total_timeout_ms;
    std::optional<size_t> max_body_bytes;
    std::optional<size_t> max_chunk_bytes;
    std::optional<int> send_timeout_ms;
};

// Server policy with any per-model override applied on top.
LiveIngestLimits resolve_live_ingest_limits(
    const LiveIngestLimits & base,
    const LiveIngestOverrides & overrides);

struct ServerModelConfig {
    struct VoicePreset {
        std::optional<std::string> voice_id;
        std::optional<std::filesystem::path> voice_ref;
        std::optional<std::string> reference_text;
        // Request options the preset supplies, passed to the model as given.
        std::unordered_map<std::string, std::string> options;
    };

    std::string id;
    std::filesystem::path path;
    std::optional<std::filesystem::path> model_spec_override;
    std::string family;
    std::string task = "tts";
    std::string mode = "offline";
    bool lazy = false;
    // Overrides ServerConfig::device for this model. When absent the server-wide
    // device remains the default, preserving existing single-device configs.
    std::optional<int> device;
    int slots = 1; // Capacity read only by the startup-selected parallel runtime.
    // Overrides ServerConfig::busy_timeout_ms for this model, and acts as the ceiling
    // a per-request busy_timeout_ms is clamped to. Model runtimes differ by orders of
    // magnitude (a short TTS clip vs. minutes of music generation), so one fleet-wide
    // bound is either too tight for the slow models or useless for the fast ones.
    std::optional<int> busy_timeout_ms;
    // Only meaningful for a streaming model reachable over the live-ingest route;
    // ignored otherwise, since no other route delivers its body incrementally.
    LiveIngestOverrides live_ingest;
    std::optional<std::string> config_id;
    std::optional<std::string> weight_id;
    std::unordered_map<std::string, std::string> load_options;
    std::unordered_map<std::string, std::string> session_options;
    std::unordered_map<std::string, std::string> default_request_options;
    std::unordered_map<std::string, VoicePreset> voice_presets;
    std::optional<VoicePreset> default_voice_preset;
    std::optional<std::string> default_voice_preset_id;
};

struct ServerConfig {
    std::string host = "127.0.0.1";
    int port = 8080;
    std::string cors_origins = "";
    bool ui_enabled = true;
    // Whether the UI was asked for (--ui, or "ui": true in the config file) rather
    // than on by default.
    bool ui_requested = false;
    bool ui_management = false;
    engine::core::BackendType backend = engine::core::BackendType::Cuda;
    std::string backend_impl;
    int device = 0;
    int threads = 1;
    bool lazy_load = false;
    bool log_request_body = false;
    uint64_t max_request_body_bytes = kDefaultMaxRequestBodyBytes;
    // A single model runs one request at a time (serialized on model.mutex). If a
    // running inference wedges the GPU -- a CUDA call that never returns cannot be
    // cancelled from userspace -- later requests would otherwise block forever, so
    // once the current run has held the lock this long a new request fails fast with
    // 503 instead of parking a worker thread. Must exceed the slowest legitimate
    // single inference (music generation can take minutes). 0 disables the guard and
    // restores unbounded waiting.
    int busy_timeout_ms = 300000;
    // Upper bound on how many models may be resident in memory at once. Loading a
    // model past the limit first unloads the least recently used idle model (its
    // next request reloads it), so a multi-model config can run on a device that
    // only fits a few of them. 1 enforces a single resident model. 0 disables the
    // limit and keeps the original behavior: once loaded, a model stays in memory
    // until it is unloaded explicitly or the server exits.
    int max_loaded_models = 0;
    // Unload every resident model once the server has been idle this long without
    // any model load/run (steady-clock ms). 0 disables idle unload. Complements
    // max_loaded_models: that bounds peak residency, this frees memory during
    // quiet periods. The next request reloads lazily.
    int idle_unload_ms = 0;
    // Minimum free memory (host and GPU, each) the server must retain after
    // loading a model, in MiB. Before every lazy load the server estimates the
    // model's resident footprint from its weights and refuses to load when
    // estimate + this headroom would not fit. 0 disables the memory guard
    // entirely (the default), so existing deployments see no behavior change
    // unless they opt in.
    int min_free_memory_mb = 0;
    // Memory for cached resampling kernels in MiB, 0 disables the cache; unset keeps the library default.
    std::optional<int> resample_kernel_cache_mb;
    // Fleet-wide bounds for incrementally delivered request bodies. The defaults are
    // in LiveIngestLimits; a model entry may override any subset of them.
    LiveIngestLimits live_ingest;
    std::string frontend_listener;
    ServerFrontendOptions frontend_options;
    std::optional<std::filesystem::path> model_spec_override;
    // Session options for every model of a family that does not set them itself:
    // the configured models and the ones loaded later through POST /v1/models/load
    // (the WebUI). Keys are family-qualified, e.g. "irodori_tts.mem_saver".
    std::unordered_map<std::string, std::string> default_session_options;
    // Voice library shared across all TTS models: *.wav files plus a `prompt_text`
    // mapping file (<basename>|<transcript>). A request `voice` name that is not a
    // model preset resolves to <voice_dir>/<name>.wav as the cloning reference.
    std::optional<std::filesystem::path> voice_dir;
    std::vector<ServerModelConfig> models;
};

engine::core::BackendType parse_server_backend(const std::string & value);
ServerConfig load_server_config(const std::filesystem::path & path);
ServerConfig load_server_config(const std::filesystem::path & path, bool parallel_jobs);
// Adds the config.default_session_options entries for model.family that the model's
// own session_options do not set.
void apply_default_session_options(const ServerConfig & config, ServerModelConfig & model);
// A WebUI load describes a model only by what its request carries. For an id the
// server config defines, takes the fields such a request cannot carry from that
// definition, while the load is still the same kind of model (family and task).
void inherit_configured_model_fields(const ServerModelConfig & configured, ServerModelConfig & model);

}  // namespace minitts::server