# === core/site_report_schema.py ===
# Single source of truth for the on-site progress metric set used by
# SiteReport.metrics (a JSONField). Edit this file to add/remove/rename
# metrics — NO database migration required, the JSONField stores
# whatever keys you save.
#
# Why this file exists:
#   The SiteReport model has structured fields (weather, temperature,
#   notes, supervisor, timestamps) AND a JSON `metrics` blob. The blob
#   stores per-day operational counts and checkboxes (e.g. how many
#   plinths were cast today, was steel tied, did the team go to town
#   for materials). These metrics will EVOLVE over time as different
#   construction phases come up — and adding a new column for every
#   change would mean a migration, a deploy, and a risk of breaking
#   historic data.
#
# How to evolve:
#   - Add a new metric: append a dict to COUNT_METRICS or CHECK_METRICS
#     with a unique snake_case `key` and a human `label`. Done. The
#     form renders it on next page load. Old reports just don't have
#     that key in their JSON — which is fine, they render as 0 / unchecked.
#   - Rename a label: change the `label` value only — the `key` stays
#     so old data still maps to the same metric.
#   - Retire a metric: delete it from this list. Old reports keep their
#     data in the JSON (it's just no longer rendered in the form). If
#     you want to fully purge it from the DB, write a one-off management
#     command — the JSON is just a Python dict at the storage layer.
#
# How NOT to use this file:
#   - Do NOT change a `key` of a metric that has data — historic reports
#     will silently lose their value for that metric. If a key really
#     must change, write a data migration that walks every SiteReport
#     and renames the JSON key.

# === COUNT METRICS ===
# Numeric counts. Form renders each as a `<input type="number" min="0">`
# with a numeric keyboard on mobile. Default value is 0 (or blank) —
# blank is treated the same as 0 when summing for reports.
COUNT_METRICS = [
    {'key': 'plinth_holes_dug',      'label': 'Plinth holes dug'},
    {'key': 'plinths_cast',          'label': 'Plinths cast'},
    {'key': 'plinths_deshuttered',   'label': 'Plinths de-shuttered'},
    {'key': 'tables_set_out',        'label': 'Tables set out'},
    {'key': 'boxes_placed',          'label': 'Boxes placed'},
    {'key': 'shutter_boxes_leveled', 'label': 'Shutter boxes leveled'},
    {'key': 'steel_placed',          'label': 'Steel placed'},
]

# === CHECK METRICS ===
# Boolean flags. Form renders each as a large-tap-target checkbox.
# Default value is False (unchecked) — absence in the JSON means False.
CHECK_METRICS = [
    {'key': 'steel_tied',     'label': 'Steel tied / built'},
    {'key': 'boxes_cleaned',  'label': 'Boxes cleaned'},
    {'key': 'town_run',       'label': 'Town for materials / food'},
    {'key': 'rain_delay',     'label': 'Rain delay'},
]


def get_count_keys():
    """Return the list of count-metric keys in display order.

    Useful for: rendering the form, validating posted data, summing
    counts across many reports for a project dashboard.
    """
    return [m['key'] for m in COUNT_METRICS]


def get_check_keys():
    """Return the list of check-metric keys in display order."""
    return [m['key'] for m in CHECK_METRICS]


def label_for(key):
    """Look up the human label for a metric key.

    Returns the key itself (snake_case) if no match — useful as a
    fallback when displaying historic data whose key has since been
    retired from the schema.
    """
    for m in COUNT_METRICS + CHECK_METRICS:
        if m['key'] == key:
            return m['label']
    return key


def empty_metrics():
    """Return a fresh metrics dict with all current keys at default values.

    Counts default to 0, checks default to False. Use as a default for
    new SiteReport instances OR as a template when comparing reports.
    """
    return {
        'counts': {m['key']: 0 for m in COUNT_METRICS},
        'checks': {m['key']: False for m in CHECK_METRICS},
    }