import QtQuick
import Quickshell.Io
import "ClockModel.js" as Model

// Supplies the two things QML cannot work out for itself: the current UTC
// offset of each configured zone, and the list of zones the picker can offer.
//
// Qt's QML engine ships no `Intl`, so there is no in-process way to render an
// IANA zone. Rather than bundle a copy of the tz database, this asks the
// system one through `date`, which keeps the bar correct across DST changes
// and tzdata updates without any code of ours needing to know the rules.
//
// The probe is cheap (one short-lived shell, a few `date` calls) and its
// result stays valid until a transition, so it runs on a slow timer instead of
// on every tick — the clocks themselves are advanced by arithmetic in between.
QtObject {
  id: root

  // zone name -> "+0200". A zone absent from here failed to resolve and is
  // rendered as unknown rather than being silently shown as UTC.
  property var offsets: ({})
  property string localOffset: ""
  // [{ zone, countries }] for the picker: the zone name plus the countries it
  // covers, so it can be found by country as well as by name.
  property var allZones: []
  property bool ready: false

  property var zones: []

  signal updated()

  // Skipping zones tzdata does not have keeps a typo out of the output
  // entirely, which is what lets the model tell "unknown zone" apart from
  // "genuinely UTC". Zone names arrive as argv, never interpolated into the
  // script, and the model has already filtered them to the tzdata name shape.
  readonly property string probeScript:
    'printf "%s\\t%s\\n" LOCAL "$(date +%z)"\n' +
    'for z in "$@"; do\n' +
    '  [ -e "/usr/share/zoneinfo/$z" ] || continue\n' +
    '  printf "%s\\t%s\\n" "$z" "$(TZ="$z" date +%z)"\n' +
    'done'

  // A probe requested while one is in flight is remembered, not dropped.
  // Config changes arrive as a burst of binding updates, so the request that
  // actually carries the newly added zone is usually not the first one — and
  // dropping it left that clock reading "--:--" until the ten-minute timer
  // came round.
  property bool probePending: false

  function probe() {
    if (probeProc.running) {
      root.probePending = true
      return
    }
    root.probePending = false
    probeProc.command = ["sh", "-c", root.probeScript, "sh"].concat(root.zones)
    probeProc.running = true
  }

  onZonesChanged: probe()

  property Process probeProc: Process {
    // Deferred so `running` has settled to false before the next probe starts.
    onExited: if (root.probePending) Qt.callLater(root.probe)

    stdout: StdioCollector {
      waitForEnd: true
      onStreamFinished: {
        var report = Model.parseOffsetReport(text)
        var local = report["LOCAL"]
        delete report["LOCAL"]
        if (local) root.localOffset = local
        root.offsets = report
        root.ready = true
        root.updated()
      }
    }
  }

  // Emits tzdata's own country tables alongside the zone list, tagged into
  // sections. The shell only reads files; the joining is done in ClockModel so
  // it can be tested. `right/` and `posix/` are pruned because they duplicate
  // every zone under a different inode, which would double the output and
  // break the alias-by-inode match.
  readonly property string catalogScript:
    'printf "@ISO\n"\n' +
    'cat /usr/share/zoneinfo/iso3166.tab 2>/dev/null\n' +
    'printf "@ZONE\n"\n' +
    'cat /usr/share/zoneinfo/zone1970.tab /usr/share/zoneinfo/zone.tab 2>/dev/null\n' +
    'printf "@INODE\n"\n' +
    'find /usr/share/zoneinfo -type f -not -path "*/right/*" -not -path "*/posix/*" ' +
      '-printf "%i\\t%P\\n" 2>/dev/null\n' +
    'printf "@LIST\n"\n' +
    'timedatectl list-timezones 2>/dev/null || ' +
      'find /usr/share/zoneinfo -type f -not -path "*/right/*" -not -path "*/posix/*" ' +
      '-printf "%P\\n" 2>/dev/null | grep -E "^[A-Z][A-Za-z_+-]*/" | sort'

  property Process zoneListProc: Process {
    command: ["sh", "-c", root.catalogScript]
    stdout: StdioCollector {
      waitForEnd: true
      onStreamFinished: root.allZones = Model.parseZoneCatalog(text)
    }
  }

  // DST transitions land on the hour, so a re-probe shortly after every hour
  // boundary catches one within a minute; the ten-minute tick is the safety
  // net for tzdata updates and suspend/resume.
  property Timer refreshTimer: Timer {
    interval: 10 * 60 * 1000
    repeat: true
    running: true
    onTriggered: root.probe()
  }

  Component.onCompleted: {
    zoneListProc.running = true
    probe()
  }
}