#!/usr/bin/python3
import difflib
import tempfile
import shutil
import os

class DtParam:
    __slots__ = ('temp', 'hyst', 'speed', 'N')
    def __init__(self, temp : int, hyst : int, speed : int, n: int):
        self.temp = temp   # Temperature in MilliCelsius
        self.hyst = hyst   # Temperature Hysteresis in MilliCelsius
        self.speed = speed # Fan Speed in 0-255
        self.N = n         # Fan Threshold number
        self._assert_valid()
        
    def _assert_valid(self):
        assert self.temp // 1000 > 0 and self.temp // 1000 < 100, f"Temperature threshold not in sensible range (0, 100) C, found {self.temp}"
        assert self.hyst // 1000 > 0 and self.hyst // 1000 < 100, f"Temperature hysteresis threshold not in sensible range (0, 100) C, found {self.temp}"
        assert self.speed >= 0 and self.speed <= 255, f"Fan speed not in value range (0, 255), found {self.speed}"
        assert self.N >= 0 and self.N <= 3, f"Threshold number not in supported set (0, 1, 2, 3), found {self.N}"
        
    def __str__(self):
        return f"dtparam=fan_temp{self.N}={self.temp},fan_temp{self.N}_hyst={self.hyst},fan_temp{self.N}_speed={self.speed}"
    

class FanCurve:
    def __init__(self):
        self.config_path = "/tmp/boot/firmware/config.txt"
        self.settings = self._get_current_settings()
        self._assert_valid_cfg()

    def update(self, settings: list[DtParam]):
        self.settings = settings
        self.settings.sort(key=lambda s: s.temp)
        for i, setting in enumerate(self.settings):
            setting.N = i
        self._assert_valid_cfg()
        self._write_cfg()
  
    def _write_cfg(self, dry_run: bool = False):
        with open(self.config_path, "r") as f:
            lines = f.readlines()
        old_cfg = [line for line in lines if not (line.startswith("dtparam=fan_temp") or line.startswith("# Auto-Generated Fan Curve"))]
        
        insert_at = None
        for i, line in enumerate(old_cfg):
            if line.strip() == "[all]":
                insert_at = i
                
        new_lines = ["# Auto-Generated Fan Curve parameters by PiFanUI\n"]
        new_lines.extend([str(setting)+"\n" for setting in self.settings])

        new_cfg = old_cfg[:insert_at + 1] + new_lines + old_cfg[insert_at + 1:]

        if new_cfg == lines:
            print("No new changes")
            return

        with tempfile.NamedTemporaryFile("w", dir="/tmp", delete=False) as new_conf:
            new_conf.writelines(new_cfg)

        diff = difflib.unified_diff(lines, new_cfg, fromfile=self.config_path, tofile=new_conf.name)

        if dry_run:
            user_dir = os.getcwd()
            with open(os.path.join(user_dir, 'PIFanTUI.patch'), 'w') as patch_file:
                patch_file.writelines(diff)                    
            print(f"Patch file generated at {os.path.join(user_dir, 'PIFanTUI.patch')}\nrun '/boot/firmware/config.txt < PIFanTUI.patch' to apply the patch")


        print(f"Updated values:")
        for line in diff:
            print(line)

        if not dry_run:
            shutil.move(new_conf.name, self.config_path)
        
    def _assert_valid_cfg(self):
        assert len(self.settings) <= 4 and len(self.settings) >= 1, f"Only up to 4 thresholds supported, found {len(self.settings)}"
        assert sorted(self.settings, key=lambda s:s.temp) == sorted(self.settings, key=lambda s:s.N), f"Thresholds are not ordered correctly:\n{[str(s) for s in self.settings]}"
        
    def _get_default_settings(self) -> list[DtParam]:
        settings = []
        settings.append(DtParam(temp=55000, hyst=2000, speed=90,  n=0))
        settings.append(DtParam(temp=65000, hyst=3000, speed=160, n=1))
        settings.append(DtParam(temp=70000, hyst=4000, speed=200, n=2))
        settings.append(DtParam(temp=72000, hyst=5000, speed=255, n=3))
        return settings

    def _get_current_settings(self) -> list[DtParam]:
        settings = []
        with open(self.config_path, "r") as f:
            lines = f.readlines()
        config_lines = [line.replace(" ", "").lower().split("#")[0][8:] for line in lines if line.startswith("dtparam=fan_temp")]
        config_lines = sorted([item[8:].replace("_", "=") for string in config_lines for item in string.split(',')])
        cfg = [item[2:].rstrip('\n') for item in config_lines]
        # TODO if not specified fill in with defaults
        assert len(cfg) % 3 == 0, "Partially Specified Fan Behaviour found, make sure to specify _temp, _hyst & _speed"
        for i in range(0, len(config_lines), 3):
            settings.append(DtParam(temp=int(cfg[i]), hyst=int(cfg[i+1][5:]), speed=int(cfg[i+2][6:]), n=i//3))
        return settings




    
def main():
    from tui import TUI
    sc = FanCurve()
    tui = TUI(sc)
    tui.run()


if __name__ == "__main__":
    main()