#define _POSIX_C_SOURCE 200809L
#include <stdlib.h>
#include <string.h>
#include "sway/input/seat.h"
#include "sway/output.h"
#include "sway/desktop/launcher.h"
#include "sway/tree/container.h"
#include "sway/tree/workspace.h"
#include "log.h"

static struct wl_list pid_workspaces;

struct pid_workspace {
	pid_t pid;
	char *workspace;
	struct timespec time_added;

	struct sway_output *output;
	struct wl_listener output_destroy;

	struct wl_list link;
};

/**
 * Get the pid of a parent process given the pid of a child process.
 *
 * Returns the parent pid or NULL if the parent pid cannot be determined.
 */
static pid_t get_parent_pid(pid_t child) {
	pid_t parent = -1;
	char file_name[100];
	char *buffer = NULL;
	const char *sep = " ";
	FILE *stat = NULL;
	size_t buf_size = 0;

	snprintf(file_name, sizeof(file_name), "/proc/%d/stat", child);

	if ((stat = fopen(file_name, "r"))) {
		if (getline(&buffer, &buf_size, stat) != -1) {
			strtok(buffer, sep); // pid
			strtok(NULL, sep);   // executable name
			strtok(NULL, sep);   // state
			char *token = strtok(NULL, sep);   // parent pid
			parent = strtol(token, NULL, 10);
		}
		free(buffer);
		fclose(stat);
	}

	if (parent) {
		return (parent == child) ? -1 : parent;
	}

	return -1;
}

static void pid_workspace_destroy(struct pid_workspace *pw) {
	wl_list_remove(&pw->output_destroy.link);
	wl_list_remove(&pw->link);
	free(pw->workspace);
	free(pw);
}

struct sway_workspace *root_workspace_for_pid(pid_t pid) {
	if (!pid_workspaces.prev && !pid_workspaces.next) {
		wl_list_init(&pid_workspaces);
		return NULL;
	}

	struct sway_workspace *ws = NULL;
	struct pid_workspace *pw = NULL;

	sway_log(SWAY_DEBUG, "Looking up workspace for pid %d", pid);

	do {
		struct pid_workspace *_pw = NULL;
		wl_list_for_each(_pw, &pid_workspaces, link) {
			if (pid == _pw->pid) {
				pw = _pw;
				sway_log(SWAY_DEBUG,
						"found pid_workspace for pid %d, workspace %s",
						pid, pw->workspace);
				goto found;
			}
		}
		pid = get_parent_pid(pid);
	} while (pid > 1);

found:
	if (pw && pw->workspace) {
		ws = workspace_by_name(pw->workspace);

		if (!ws) {
			sway_log(SWAY_DEBUG,
					"Creating workspace %s for pid %d because it disappeared",
					pw->workspace, pid);

			struct sway_output *output = pw->output;
			if (pw->output && !pw->output->enabled) {
				sway_log(SWAY_DEBUG,
						"Workspace output %s is disabled, trying another one",
						pw->output->wlr_output->name);
				output = NULL;
			}

			ws = workspace_create(output, pw->workspace);
		}

		pid_workspace_destroy(pw);
	}

	return ws;
}

static void pw_handle_output_destroy(struct wl_listener *listener, void *data) {
	struct pid_workspace *pw = wl_container_of(listener, pw, output_destroy);
	pw->output = NULL;
	wl_list_remove(&pw->output_destroy.link);
	wl_list_init(&pw->output_destroy.link);
}

void root_record_workspace_pid(pid_t pid) {
	sway_log(SWAY_DEBUG, "Recording workspace for process %d", pid);
	if (!pid_workspaces.prev && !pid_workspaces.next) {
		wl_list_init(&pid_workspaces);
	}

	struct sway_seat *seat = input_manager_current_seat();
	struct sway_workspace *ws = seat_get_focused_workspace(seat);
	if (!ws) {
		sway_log(SWAY_DEBUG, "Bailing out, no workspace");
		return;
	}
	struct sway_output *output = ws->output;
	if (!output) {
		sway_log(SWAY_DEBUG, "Bailing out, no output");
		return;
	}

	struct timespec now;
	clock_gettime(CLOCK_MONOTONIC, &now);

	// Remove expired entries
	static const int timeout = 60;
	struct pid_workspace *old, *_old;
	wl_list_for_each_safe(old, _old, &pid_workspaces, link) {
		if (now.tv_sec - old->time_added.tv_sec >= timeout) {
			pid_workspace_destroy(old);
		}
	}

	struct pid_workspace *pw = calloc(1, sizeof(struct pid_workspace));
	pw->workspace = strdup(ws->name);
	pw->output = output;
	pw->pid = pid;
	memcpy(&pw->time_added, &now, sizeof(struct timespec));
	pw->output_destroy.notify = pw_handle_output_destroy;
	wl_signal_add(&output->wlr_output->events.destroy, &pw->output_destroy);
	wl_list_insert(&pid_workspaces, &pw->link);
}

void root_remove_workspace_pid(pid_t pid) {
	if (!pid_workspaces.prev || !pid_workspaces.next) {
		return;
	}

	struct pid_workspace *pw, *tmp;
	wl_list_for_each_safe(pw, tmp, &pid_workspaces, link) {
		if (pid == pw->pid) {
			pid_workspace_destroy(pw);
			return;
		}
	}
}

void root_rename_pid_workspaces(const char *old_name, const char *new_name) {
	if (!pid_workspaces.prev && !pid_workspaces.next) {
		wl_list_init(&pid_workspaces);
	}

	struct pid_workspace *pw = NULL;
	wl_list_for_each(pw, &pid_workspaces, link) {
		if (strcmp(pw->workspace, old_name) == 0) {
			free(pw->workspace);
			pw->workspace = strdup(new_name);
		}
	}
}