// SPDX-License-Identifier: MIT
// SPDX-FileCopyrightText: 2026 Martino Ferrari
#pragma once

#include <cstdint>
#include <string>
#include <vector>

#include "math_channel.hpp"
#include "measure.hpp"

namespace udpscope {

/// The user-arranged part of a session, persisted per data source in
/// `~/.config/udpscope/<host>_<port>.toml`: the display window, the plot layout
/// (rows and which signal each of a row's slots holds) and the per-signal
/// calibration. Signal names are the stable identity (channel indexes are
/// renumbered by every enable/disable, see the model's own invariant).
struct LayoutState {
  struct Row {
    /// One entry per slot; an empty string is an empty slot.
    std::vector<std::string> signals;
    /// The row's share of the figure's height, 1 for equal rows. Part of the layout because a sizing a
    /// user dragged is an arrangement, and an arrangement that is not saved is one that is lost.
    double weight = 1.0;
  };

  double window_s = 0.0;  ///< 0 keeps the default window
  std::vector<Row> rows;

  struct Calibration {
    std::string name;
    double gain = 1.0;
    double offset = 0.0;
  };
  std::vector<Calibration> calibration;

  /// The trace colours the user chose, `0xRRGGBB`. Only the *overrides*: a signal with no entry
  /// takes the positional palette entry, which is what keeps a stream's new signals coloured
  /// without a session having to name them. Saved by name like every identity here.
  struct Color {
    std::string name;
    std::uint32_t rgb = 0;
  };
  std::vector<Color> colors;

  /// Signals the session had enabled. Enabling is what starts acquisition, so this is what makes a
  /// reopened scope look like the one that was closed -- and it is saved by *name*, like every other
  /// identity here, because a CONFIG renumbers the channels.
  std::vector<std::string> enabled;

  /// How this source was reached, so the startup chooser can reconnect to it exactly. The file is
  /// named `<host>_<port>.toml` and that name can say neither of these. Empty `multicast` is
  /// unicast; empty `interface_addr` is the default route.
  std::string multicast;
  std::string interface_addr;

  /// The derived channels, graphs and all: the editor's work is part of the session, not of the
  /// process. A graph is stored as one string per node so the file stays in this store's TOML
  /// subset (tables, string arrays, scalars) rather than growing a nested-table parser for it; see
  /// `math_node_text()` for the field order.
  std::vector<MathChannel> math;

  /// Whether the measurements pane shows its statistics line. The only piece of the
  /// statistics that is persisted: the accumulated figures themselves describe a session's
  /// stream and mean nothing restored against another one.
  bool measure_stats = false;

  /// The measurements pane, by signal *name* and with the type and options a row was built with.
  std::vector<Measure> measures;

  /// Free text the user attached to this configuration: what it is for, what to look at first.
  /// A configuration is a *named* session, and the name alone rarely says what makes it different
  /// from its neighbour.
  std::string comment;

  /// The startup settings the configuration carries, applied when the chooser opens it -- which is
  /// why they live here and not only on the command line: two sources on one machine want different
  /// buffers and different clocks, and retyping the flags to look at the second one is how a
  /// setting gets forgotten. A zero `buffer_mb` and an empty `capture_packets` mean "not stored":
  /// the command line's value stands, so an old file cannot silently shrink a buffer.
  double buffer_mb = 0.0;
  bool relative_time = false;
  std::uint32_t capture_packets = 0;
};

/// A data source udpscope has a stored session for: one row of the startup chooser.
struct KnownSource {
  std::string host;            ///< the CONFIG server, even for a multicast session
  std::uint16_t port = 0;
  std::string multicast;       ///< empty = unicast
  std::string interface_addr;  ///< empty = the default route
  int rows = 0;                ///< plots the session had
  int signals = 0;             ///< named slots across those plots
  std::int64_t mtime = 0;      ///< orders the list; never shown
  /// Which *configuration* of that source this row is. A source may have several, each a named
  /// session of its own, so the pair (host, port, config) is what identifies a row.
  std::string config;
  std::string comment;         ///< the configuration's note, shown beside its name
  /// The startup settings this configuration carries, so the chooser can apply them.
  double buffer_mb = 0.0;
  bool relative_time = false;
  std::uint32_t capture_packets = 0;
};

/// Every configuration that names at least one signal *or* carries a setting, newest first.
///
/// The filter is what makes the list usable: a development machine accumulates one session file
/// per probe run on a throwaway port -- 140 of them when this was written -- and every one holds
/// `signals = ["", "", "", ""]`. A listed source is one somebody actually configured — and a
/// buffer size, a note or a clock counts as configuring it, because that is how the chooser's form
/// sets a host up before it has ever streamed.
std::vector<KnownSource> known_sources();

/// Deletes one source's session file; the chooser's `x`. False means the file was already gone or
/// could not be removed, which costs the caller nothing -- there is no state to roll back.
bool forget_source(const KnownSource& src);

/// One `MathNode` as `kind|source|in_a|in_b|gain|offset|fc|q|lo|hi|x|y`, and back. The kind is the
/// op's *index* into `math_op_at()`, which is why the enum's order is a stored format and not just
/// an implementation detail: reordering it renames every saved graph's operations.
std::string math_node_text(const MathNode& node);
bool math_node_from_text(const std::string& text, MathNode& out);

/// The directory session files live in: $XDG_CONFIG_HOME/udpscope, else
/// ~/.config/udpscope, else /tmp/udpscope-config. Not created by this call.
std::string config_dir();
/// `$XDG_CACHE_HOME/udpscope`, or `~/.cache/udpscope`: where bulky, disposable state
/// lives (the packet captures; item 9's event cache). Created on demand by callers.
std::string cache_dir();

/// Creates `path` and every missing component, like `mkdir -p`. Public because the preferences are
/// written under the config directory too.
void mkdirs(const std::string& path);

/// The *legacy* single-file path, `~/.config/udpscope/<host>_<port>.toml`, with the directory
/// created. Still the import source for a file written before configurations existed; nothing
/// writes here any more.
std::string layout_path(const std::string& host, std::uint16_t port);

/// The per-source directory a source's configurations live in:
/// `~/.config/udpscope/<host>_<port>/`. Not created by this call.
std::string config_dir_for(const std::string& host, std::uint16_t port);

/// One configuration's file, `<config_dir_for(host, port)>/<name>.toml`, with the directory
/// created. The name is sanitized the way the host is, so a name the user typed with a slash in it
/// cannot escape the directory.
std::string configuration_path(const std::string& host, std::uint16_t port,
                               const std::string& name);

/// The source's configurations, newest first. A legacy single-file session appears here as the
/// configuration named `default`, and importing it is the first thing this does.
std::vector<std::string> configuration_names(const std::string& host, std::uint16_t port);

/// The configuration the source was last left in: `<dir>/active`, or the newest that exists when
/// nothing wrote one. Never empty for a source that has any configuration at all.
std::string active_configuration(const std::string& host, std::uint16_t port);

/// Remembers which configuration this source is on. Called by every save.
bool set_active_configuration(const std::string& host, std::uint16_t port, const std::string& name);

/// Deletes one configuration's file, and `active` if it named it.
bool forget_configuration(const std::string& host, std::uint16_t port, const std::string& name);

/// Parses the file's TOML subset. Returns false when the file is missing or
/// malformed; `out` is left usable either way (a malformed file loads as much as
/// parsed, which beats refusing a hand-edited file over one stray character).
bool load_layout(const std::string& path, LayoutState& out);

/// Writes `state` as TOML. Atomic in effect: writes a sibling temp file and
/// renames it over the target.
bool save_layout(const std::string& path, const LayoutState& state);

}  // namespace udpscope