use anyhow::{Result, anyhow};
use std::path::{Path};
use std::fs;
use std::time::{Duration, Instant};
use std::sync::Mutex;

use crate::sal::traits::{SensorBus, ActuatorBus, EnvironmentGuard, HardwareWatchdog, PreflightAuditor, AuditStep, AuditError, SafetyStatus, EnvironmentCtx};
use crate::sal::safety::{TdpLimitMicroWatts, FanSpeedPercentage};
use crate::sal::heuristic::discovery::SystemFactSheet;
use crate::sal::heuristic::schema::HardwareDb;

pub struct GenericLinuxSal {
    ctx: EnvironmentCtx,
    fact_sheet: SystemFactSheet,
    db: HardwareDb,
    suppressed_services: Mutex<Vec<String>>,
    last_valid_temp: Mutex<(f32, Instant)>,
    current_pl1: Mutex<u64>,
    last_energy: Mutex<(u64, Instant)>,

    // --- Original State for Restoration ---
    original_pl1: Mutex<Option<u64>>,
    original_pl2: Mutex<Option<u64>>,
}

impl GenericLinuxSal {
    pub fn new(ctx: EnvironmentCtx, facts: SystemFactSheet, db: HardwareDb) -> Self {
        let initial_energy = if let Some(pwr_base) = facts.rapl_paths.first() {
            fs::read_to_string(pwr_base.join("energy_uj")).unwrap_or_default().trim().parse().unwrap_or(0)
        } else {
            0
        };

        Self {
            db,
            suppressed_services: Mutex::new(Vec::new()),
            last_valid_temp: Mutex::new((0.0, Instant::now())),
            current_pl1: Mutex::new(15_000_000),
            last_energy: Mutex::new((initial_energy, Instant::now())),
            fact_sheet: facts,
            ctx,
            original_pl1: Mutex::new(None),
            original_pl2: Mutex::new(None),
        }
    }

    fn is_dell(&self) -> bool {
        self.fact_sheet.vendor.to_lowercase().contains("dell")
    }

    fn read_sysfs(&self, path: &Path) -> Result<String> {
        fs::read_to_string(path).map(|s| s.trim().to_string()).map_err(|e| anyhow!(e))
    }
}

impl PreflightAuditor for GenericLinuxSal {
    fn audit(&self) -> Box<dyn Iterator<Item = AuditStep> + '_> {
        let mut steps = Vec::new();
        for check in &self.db.preflight_checks {
            let status = self.ctx.runner.run("sh", &["-c", &check.check_cmd]);
            steps.push(AuditStep {
                description: check.name.clone(),
                outcome: match status {
                    Ok(_) => Ok(()),
                    _ => Err(AuditError::KernelIncompatible(check.fail_help.clone())),
                }
            });
        }
        for conflict_id in &self.fact_sheet.active_conflicts {
            if let Some(conflict) = self.db.conflicts.iter().find(|c| &c.id == conflict_id) {
                if conflict.severity == "Critical" {
                    steps.push(AuditStep {
                        description: format!("Conflict: {}", conflict.id),
                        outcome: Err(AuditError::ToolMissing(conflict.help_text.clone())),
                    });
                }
            }
        }
        Box::new(steps.into_iter())
    }
}

impl SensorBus for GenericLinuxSal {
    fn get_temp(&self) -> Result<f32> {
        let path = self.fact_sheet.temp_path.as_ref()
            .ok_or_else(|| anyhow!("No temperature sensor path found"))?;
        let content = self.read_sysfs(path)?;
        let temp = content.parse::<f32>()? / 1000.0;
        let mut last = self.last_valid_temp.lock().unwrap();
        if (temp - last.0).abs() > 0.01 { *last = (temp, Instant::now()); }
        Ok(temp)
    }

    fn get_power_w(&self) -> Result<f32> {
        let rapl_path = self.fact_sheet.rapl_paths.first()
            .ok_or_else(|| anyhow!("No RAPL path found"))?;
        let energy_path = rapl_path.join("energy_uj");
        let mut last = self.last_energy.lock().unwrap();
        let e2: u64 = self.read_sysfs(&energy_path)?.parse()?;
        let t2 = Instant::now();
        let (e1, t1) = *last;
        let delta_e = e2.wrapping_sub(e1);
        let delta_t = t2.duration_since(t1).as_secs_f32();
        *last = (e2, t2);
        if delta_t < 0.05 { return Ok(0.0); }
        Ok((delta_e as f32 / 1_000_000.0) / delta_t)
    }

    fn get_fan_rpms(&self) -> Result<Vec<u32>> {
        let mut rpms = Vec::new();
        for path in &self.fact_sheet.fan_paths {
            if let Ok(content) = self.read_sysfs(path) {
                if let Ok(rpm) = content.parse() { rpms.push(rpm); }
            }
        }
        Ok(rpms)
    }

    fn get_freq_mhz(&self) -> Result<f32> {
        let path = self.ctx.sysfs_base.join("sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq");
        if path.exists() {
            Ok(self.read_sysfs(&path)?.parse::<f32>()? / 1000.0)
        } else {
            let cpuinfo_path = self.ctx.sysfs_base.join("proc/cpuinfo");
            let cpuinfo = fs::read_to_string(cpuinfo_path)?;
            for line in cpuinfo.lines() {
                if line.starts_with("cpu MHz") {
                    if let Some((_, mhz)) = line.split_once(':') {
                        return Ok(mhz.trim().parse()?);
                    }
                }
            }
            Err(anyhow!("Could not determine CPU frequency"))
        }
    }

    fn get_throttling_status(&self) -> Result<bool> {
        // Fallback: check if any cooling device is active (cur_state > 0)
        let cooling_base = self.ctx.sysfs_base.join("sys/class/thermal");
        if let Ok(entries) = fs::read_dir(cooling_base) {
            for entry in entries.flatten() {
                if entry.file_name().to_string_lossy().starts_with("cooling_device") {
                    if let Ok(state) = fs::read_to_string(entry.path().join("cur_state")) {
                        if state.trim().parse::<u32>().unwrap_or(0) > 0 {
                            return Ok(true);
                        }
                    }
                }
            }
        }
        Ok(false)
    }
}

impl ActuatorBus for GenericLinuxSal {
    fn set_fan_mode(&self, mode: &str) -> Result<()> {
        if self.is_dell() {
            let cmd = match mode {
                "manual" | "max" => self.db.ecosystems.get("dell").and_then(|e| e.fan_manual_mode_cmd.as_ref()),
                "auto" => self.db.ecosystems.get("dell").and_then(|e| e.fan_auto_mode_cmd.as_ref()),
                _ => return Err(anyhow!("Unsupported fan mode: {}", mode)),
            };
            if let Some(cmd_str) = cmd {
                let parts: Vec<&str> = cmd_str.split_whitespace().collect();
                self.ctx.runner.run(parts[0], &parts[1..])?;
                Ok(())
            } else { Err(anyhow!("Dell fan command missing")) }
        } else { Ok(()) }
    }

    fn set_fan_speed(&self, _speed: FanSpeedPercentage) -> Result<()> {
        Ok(())
    }

    fn set_sustained_power_limit(&self, limit: TdpLimitMicroWatts) -> Result<()> {
        let rapl_path = self.fact_sheet.rapl_paths.first().ok_or_else(|| anyhow!("No PL1 path"))?;
        fs::write(rapl_path.join("constraint_0_power_limit_uw"), limit.as_u64().to_string())?;
        *self.current_pl1.lock().unwrap() = limit.as_u64();
        Ok(())
    }

    fn set_burst_power_limit(&self, limit: TdpLimitMicroWatts) -> Result<()> {
        let rapl_path = self.fact_sheet.rapl_paths.first().ok_or_else(|| anyhow!("No PL2 path"))?;
        fs::write(rapl_path.join("constraint_1_power_limit_uw"), limit.as_u64().to_string())?;
        Ok(())
    }
}

impl EnvironmentGuard for GenericLinuxSal {
    fn suppress(&self) -> Result<()> {
        // Snapshot Power Limits
        if let Some(rapl_path) = self.fact_sheet.rapl_paths.first() {
            if let Ok(pl1) = fs::read_to_string(rapl_path.join("constraint_0_power_limit_uw")) {
                *self.original_pl1.lock().unwrap() = pl1.trim().parse().ok();
            }
            if let Ok(pl2) = fs::read_to_string(rapl_path.join("constraint_1_power_limit_uw")) {
                *self.original_pl2.lock().unwrap() = pl2.trim().parse().ok();
            }
        }

        let mut suppressed = self.suppressed_services.lock().unwrap();
        for conflict_id in &self.fact_sheet.active_conflicts {
            if let Some(conflict) = self.db.conflicts.iter().find(|c| &c.id == conflict_id) {
                for service in &conflict.services {
                    if self.ctx.runner.run("systemctl", &["is-active", "--quiet", service]).is_ok() {
                        let _ = self.ctx.runner.run("systemctl", &["stop", service]);
                        suppressed.push(service.clone());
                    }
                }
            }
        }
        Ok(())
    }

    fn restore(&self) -> Result<()> {
        // Restore Power Limits
        if let Some(rapl_path) = self.fact_sheet.rapl_paths.first() {
            if let Some(pl1) = *self.original_pl1.lock().unwrap() {
                let _ = fs::write(rapl_path.join("constraint_0_power_limit_uw"), pl1.to_string());
            }
            if let Some(pl2) = *self.original_pl2.lock().unwrap() {
                let _ = fs::write(rapl_path.join("constraint_1_power_limit_uw"), pl2.to_string());
            }
        }

        let mut suppressed = self.suppressed_services.lock().unwrap();
        for service in suppressed.drain(..) {
            let _ = self.ctx.runner.run("systemctl", &["start", &service]);
        }
        if self.is_dell() { let _ = self.set_fan_mode("auto"); }
        Ok(())
    }
}

impl HardwareWatchdog for GenericLinuxSal {
    fn get_safety_status(&self) -> Result<SafetyStatus> {
        let temp = self.get_temp()?;
        if temp > 100.0 {
            return Ok(SafetyStatus::EmergencyAbort(format!("Thermal runaway: {:.1}°C", temp)));
        }
        let last = self.last_valid_temp.lock().unwrap();
        if last.1.elapsed() > Duration::from_secs(5) {
            return Ok(SafetyStatus::EmergencyAbort("Temperature sensor stalled".to_string()));
        }
        Ok(SafetyStatus::Nominal)
    }
}

impl Drop for GenericLinuxSal {
    fn drop(&mut self) { let _ = self.restore(); }
}