/**
 * Copyright 2019 Shawn Anastasio
 *
 * This file is part of op-fan-daemon.
 *
 * op-fan-daemon is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * op-fan-daemon is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with op-fan-daemon.  If not, see <https://www.gnu.org/licenses/>.
 */

/**
 * A simple fan daemon for OpenPOWER systems
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <stdint.h>
#include <errno.h>
#include <inttypes.h>
#include <assert.h>

#include <dirent.h>
#include <fcntl.h>
#include <signal.h>
#include <syslog.h>
#include <sys/select.h>
#include <sys/signalfd.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>

#define DECLARE_CURVES 1
#include "fan-daemon.h"
#include "control.h"
#include "curve.h"
#include "util.h"

#define REASONABLE_PATH_LEN 1024

const char cpu0_sensors_path[] = "/sys/devices/platform/gpio-fsi/fsi0/slave@00:00/00:00:00:06/sbefifo1-dev0";
const char cpu1_sensors_path[] = "/sys/devices/platform/gpio-fsi/fsi0/slave@00:00/00:00:00:0a/fsi1/slave@01:00/01:01:00:06/sbefifo2-dev0";

// Globally registered PWM providers
struct pwm_ops *pwm_providers[NUM_PWM_PROVIDERS] = { 0 };
struct pwm_ops *pwm_provider = NULL;

void install_pwm_provider(struct pwm_ops *ops) {
    for (size_t i=0; i<NUM_PWM_PROVIDERS; i++) {
        if (!pwm_providers[i]) {
            pwm_providers[i] = ops;
            return;
        }
    }

    fprintf(stderr, "FATAL: Unable to install pwm provider: not enough space.\n");
    exit(EXIT_FAILURE);
}

/**
 * Initialize a sensor group from a given path.
 *
 * @param      path      path to OCC sbefifo device in /sys
 * @param[out] group_out sensor_group struct to initialize on success
 * @return               success?
 */
static bool open_sensor_group(const char *path, struct sensor_group *group_out) {
    bool ret = false;
    char pathbuf[REASONABLE_PATH_LEN];
    char occ_hwmon_name[12 + 1 /* strlen("occ-hwmon.XX") */];
    struct dirent *child;

    DIR *base = opendir(path);
    if (!base) {
        syslog(LOG_ERR, "Couldn't open provided path!\n");
        goto out;
    }

    // Walk fs to get to occ-hwmon.*/hwmon directory
    DIR *occ_hwmon = NULL;
    while ((child = readdir(base))) {
        if (child->d_name[0] == '.')
            continue; // Skip hidden, ".", ".."

        if (!strncmp("occ-hwmon.", child->d_name, 9)) {
            snprintf(pathbuf, sizeof(pathbuf), "%s/%s/hwmon", path, child->d_name);
            occ_hwmon = opendir(pathbuf);

            strncpy(occ_hwmon_name, child->d_name, sizeof(occ_hwmon_name) - 1);
            occ_hwmon_name[sizeof(occ_hwmon_name) - 1] = '\0';
            break;
        }
    }

    if (!occ_hwmon) {
        syslog(LOG_ERR, "Couldn't find occ_hwmon!\n");
        goto out_base;
    }

    // Walk fs to get to hwmonN directory
    DIR *hwmonN = NULL;
    while ((child = readdir(occ_hwmon))) {
        if (child->d_name[0] == '.')
            continue; // Skip hidden, ".", ".."

        if (!strncmp("hwmon", child->d_name, 5)) {
            snprintf(pathbuf, sizeof(pathbuf), "%s/%s/hwmon/%s", path, occ_hwmon_name, child->d_name);
            hwmonN = opendir(pathbuf);
            break;
        }
    }

    if (!hwmonN) {
        syslog(LOG_ERR, "Couldn't find hwmonN!\n");
        goto out_occ_hwmon;
    }

    // Successfully found and opened the appropriate hwmon directory, return it.
    group_out->dir = hwmonN;
    strncpy(group_out->dir_path, pathbuf, sizeof(group_out->dir_path) - 1);
    group_out->dir_path[sizeof(group_out->dir_path) - 1] = '\0';
    ret = true;

out_occ_hwmon:
    closedir(occ_hwmon);
out_base:
    closedir(base);
out:
    return ret;
}

/**
 * Populate a given list of sensors with all sensors in a given group that
 * match a given FRU.
 *
 * @param list          list to populate
 * @param group         sensors group to search in
 * @param desired_fru   FRU to filter by
 * @return success?
 */
static bool populate_sensor_list(struct vec_int *list, struct sensor_group *group, uint8_t desired_fru) {
    char pathbuf[REASONABLE_PATH_LEN + 256 /* d_name field is 256 bytes wide */];
    struct dirent *child;

    // Walk sensor directory for *_fru_type nodes and read them
    rewinddir(group->dir);
    while ((child = readdir(group->dir))) {
        if (child->d_name[0] == '.')
            continue; // Skip hidden, ".", ".."

        if (!strstr(child->d_name, "_fru_type"))
            continue; // Not what we're looking for

        // Read FRU
        snprintf(pathbuf, sizeof(pathbuf), "%s/%s", group->dir_path, child->d_name);
        int type_fd = open(pathbuf, O_RDONLY);
        if (type_fd < 0)
            goto skip_sensor;

        char fru_str[2 + 1 /* strlen("00") */];
        ssize_t n;
        if ((n = read(type_fd, fru_str, sizeof(fru_str) - 1)) < 0) {
            close(type_fd);
            goto skip_sensor;
        }
        fru_str[n] = '\0';
        close(type_fd);

        // Convert FRU to number
        char *endptr;
        long fru = strtol(fru_str, &endptr, 10);
        if (*endptr != '\n' && *endptr != '\0')
            goto skip_sensor;

        // See if FRU matches
        if (fru != desired_fru)
            continue;

        // Open fd to this sensor's input file and append to list
        uint8_t num;
        sscanf(child->d_name, "temp%" SCNu8 "_fru_type", &num);

        snprintf(pathbuf, sizeof(pathbuf), "%s/temp%" PRIu8 "_input", group->dir_path, num);
        int sensor_fd = open(pathbuf, O_RDONLY);
        if (sensor_fd < 0)
            goto skip_sensor;

        vec_int_push_back(list, sensor_fd);

        continue;
    skip_sensor:
        syslog(LOG_INFO, "Failed to read sensor %s: %m.\n", child->d_name);
    }

    return true;
}

/**
 * Initialize sensors and platform PWM controller
 */
struct controller_state *controller_init(void) {
    struct controller_state *state = calloc(1, sizeof(struct controller_state));
    if (!state) {
        syslog(LOG_ERR, "Unable to allocate program state: %m.\n");
        return NULL;
    }

    if (!vec_int_init(&state->zones[ZONE_CPU0].sensors, 50, close_destructor) ||
        !vec_int_init(&state->zones[ZONE_CPU1].sensors, 50, close_destructor) ||
        !vec_int_init(&state->zones[ZONE_CHASSIS].sensors, 50, close_destructor)) {
        syslog(LOG_ERR, "Unable to allocate sensor lists: %m.\n");
        goto fail;
    }

    // Select fan curves to use for each zone
    state->zones[ZONE_CPU0].curve = zone_cpu0_curve;
    state->zones[ZONE_CPU0].curve_size = ARRAY_SIZE(zone_cpu0_curve);
    state->zones[ZONE_CPU0].curve_pos = ARRAY_SIZE(zone_cpu0_curve) - 1;
    state->zones[ZONE_CPU0].next_curve_pos = 0;
    state->zones[ZONE_CPU0].next_curve_count = 0;

    state->zones[ZONE_CPU1].curve = zone_cpu1_curve;
    state->zones[ZONE_CPU1].curve_size = ARRAY_SIZE(zone_cpu1_curve);
    state->zones[ZONE_CPU1].curve_pos = ARRAY_SIZE(zone_cpu1_curve) - 1;
    state->zones[ZONE_CPU1].next_curve_pos = 0;
    state->zones[ZONE_CPU1].next_curve_count = 0;

    state->zones[ZONE_CHASSIS].curve = zone_chassis_curve;
    state->zones[ZONE_CHASSIS].curve_size = ARRAY_SIZE(zone_chassis_curve);
    state->zones[ZONE_CHASSIS].curve_pos = ARRAY_SIZE(zone_chassis_curve) - 1;
    state->zones[ZONE_CHASSIS].next_curve_pos = 0;
    state->zones[ZONE_CHASSIS].next_curve_count = 0;

    // Open sensor groups
    if (!open_sensor_group(cpu0_sensors_path, &state->occ0)) {
        syslog(LOG_ERR, "Unable to open OCC sensors for CPU0: %m.\n");
        goto fail;
    }

    if (!open_sensor_group(cpu1_sensors_path, &state->occ1))
        syslog(LOG_INFO, "Unable to open OCC sensors for CPU1, assuming single socket system (%m).\n");
    else
        state->flags |= STATE_FLAG_CPU1_PRESENT;


    // Populate zone sensor lists
    if (!populate_sensor_list(&state->zones[ZONE_CPU0].sensors, &state->occ0, FRU_TYPE_CORE)) {
        syslog(LOG_ERR, "Unable to populate sensor list for CPU0: %m.\n");
        goto fail;
    }

    if (!populate_sensor_list(&state->zones[ZONE_CHASSIS].sensors, &state->occ0, FRU_TYPE_DIMM)) {
        syslog(LOG_ERR, "Unable to populate sensor list for Chassis (DIMM, OCC0): %m.\n");
        goto fail;
    }

    if (!populate_sensor_list(&state->zones[ZONE_CHASSIS].sensors, &state->occ0, FRU_TYPE_VRM_VDD)) {
        syslog(LOG_ERR, "Unable to populate sensor list for Chassis (VRM_VDD, OCC0): %m.\n");
        goto fail;
    }

    // If OCC1 is present, populate its sensors too
    if (state->flags & STATE_FLAG_CPU1_PRESENT) {
        if (!populate_sensor_list(&state->zones[ZONE_CPU1].sensors, &state->occ1, FRU_TYPE_CORE)) {
            syslog(LOG_ERR, "Unable to populate sensor list for CPU1: %m.\n");
            goto fail;
        }

        if (!populate_sensor_list(&state->zones[ZONE_CHASSIS].sensors, &state->occ1, FRU_TYPE_DIMM)) {
            syslog(LOG_ERR, "Unable to populate sensor list for Chassis (DIMM, OCC1): %m.\n");
            goto fail;
        }

        if (!populate_sensor_list(&state->zones[ZONE_CHASSIS].sensors, &state->occ1, FRU_TYPE_VRM_VDD)) {
            syslog(LOG_ERR, "Unable to populate sensor list for Chassis (VRM_VDD, OCC1): %m.\n");
            goto fail;
        }
    }

    return state;

fail:
    // Cleanup any members that were initialized
    if (state->occ0.dir)
        closedir(state->occ0.dir);
    if (state->occ1.dir)
        closedir(state->occ1.dir);
    for (size_t i=0; i<NUM_ZONES; i++) {
        if (state->zones[i].sensors.data)
            vec_int_destroy(&state->zones[i].sensors);
    }

    return NULL;
}

static void controller_destroy(struct controller_state *state) {
    closedir(state->occ0.dir);

    vec_int_destroy(&state->zones[ZONE_CPU0].sensors);
    vec_int_destroy(&state->zones[ZONE_CHASSIS].sensors);

    if (state->flags & STATE_FLAG_CPU1_PRESENT) {
        closedir(state->occ1.dir);
        vec_int_destroy(&state->zones[ZONE_CPU1].sensors);
    }

    free(state);
}

bool get_next_mode(int sigfd, bool cur_mode) {
    // select(2) on the signalfd or timeout
    fd_set fds;
    FD_ZERO(&fds);
    FD_SET(sigfd, &fds);
    struct timeval timeout = { .tv_usec = POLL_DELAY_US };
    if (select(sigfd + 1, &fds, NULL, NULL, &timeout) < 0)
        goto fail;

    if (FD_ISSET(sigfd, &fds)) {
        struct signalfd_siginfo siginfo;
        if (read(sigfd, &siginfo, sizeof(siginfo)) < 0)
            goto fail;

        if (siginfo.ssi_signo == SIGUSR1)
            return false; // Disable fan control
        else if (siginfo.ssi_signo == SIGUSR2)
            return true; // Enable fan control
        else
            syslog(LOG_WARNING, "Unknown signal received (%d). Ignoring.\n", siginfo.ssi_signo);
    }

    // Timeout reached or unknown signal, return current mode
    return cur_mode;

fail:
    syslog(LOG_ERR, "Error encountered while polling: %m. Disabling fan control.\n");
    return false;
}

int main(int argc, char **argv) {
    openlog("fan-daemon", LOG_NDELAY, LOG_USER);

    // Find PWM provider
    for (size_t i=0; i<NUM_PWM_PROVIDERS; i++) {
        if (pwm_providers[i] && pwm_providers[i]->probe()) {
            pwm_provider = pwm_providers[i];
            break;
        }
    }

    if (!pwm_provider) {
        syslog(LOG_ERR, "Failed to autodetect platform! Exiting.\n");
        return EXIT_FAILURE;
    }

    //struct controller_state *state = controller_init();
    //print_zones(state);

    /**
     * Program state is controlled via signals.
     * SIGUSR1 - Fan control disabled, max out all zones. Used during IPL.
     * SIGUSR2 - Fan control enabled, read OCC sensors and follow curve.
     *
     * Create a signalfd to receive these.
     */
    sigset_t ss;
    sigemptyset(&ss);
    sigaddset(&ss, SIGUSR1);
    sigaddset(&ss, SIGUSR2);
    int sigfd = signalfd(-1, &ss, 0);
    if (sigfd < 0) {
        syslog(LOG_ERR, "Failed to create signalfd: %m. Exiting.\n");
        return EXIT_FAILURE;
    }

    // Now that we can receive them via a signalfd, block them
    if (sigprocmask(SIG_BLOCK, &ss, NULL) < 0) {
        syslog(LOG_ERR, "Failed to block signals: %m. Exiting.\n");
        return EXIT_FAILURE;
    }

    bool enable_control = false;
    bool fault = false;
    struct controller_state *state = NULL;
    for(;;) {
        // Get next mode
        bool next = get_next_mode(sigfd, enable_control) && !fault;

        // Check if mode changed and perform switch
        if (next != enable_control) {
            enable_control = next;
            if (next) {
                // Disable->Enable, re-initalize controller state
                dbg_printf("Enabling fan control!\n");
                if (!(state = controller_init())) {
                    syslog(LOG_ERR, "Failed to allocate state! Disabling fan control.\n");
                    enable_control = false;
                }
            } else {
                // Enable->Disable, destroy controller state
                dbg_printf("Disabling fan control!\n");
                controller_destroy(state);
            }
        }

        // Clear any previous faults
        fault = false;

        // Control fans
        if (enable_control) {
            // Run control algorithm on all zones
            if (!update_zone(state, ZONE_CPU0))
                fault = true;

            if (state->flags & STATE_FLAG_CPU1_PRESENT)
                if (!update_zone(state, ZONE_CPU1))
                    fault = true;

            if (!update_zone(state, ZONE_CHASSIS))
                fault = true;
        } else {
            // Fan control disabled, max out all fans
            pwm_provider->set_zone_speed(ZONE_CPU0, 255);
            pwm_provider->set_zone_speed(ZONE_CPU1, 255);
            pwm_provider->set_zone_speed(ZONE_CHASSIS, 255);
        }
    }
}