-- supabase/migrations/20260709000004_evidence_investigations.sql
CREATE TYPE evidence_stage AS ENUM (
  'report', 'response', 'investigation', 'capa', 'verification'
);

CREATE TABLE evidence_files (
  id          UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  incident_id UUID NOT NULL REFERENCES incidents(id) ON DELETE RESTRICT,
  stage       evidence_stage NOT NULL,
  file_url    TEXT NOT NULL,
  file_type   TEXT NOT NULL,
  file_hash   TEXT NOT NULL,        -- immutable after upload (DOSH audit integrity)
  uploaded_by UUID NOT NULL REFERENCES users(id),
  uploaded_at TIMESTAMPTZ NOT NULL DEFAULT now(),
  deleted     BOOLEAN NOT NULL DEFAULT false  -- NEVER hard-delete; use this flag
);

CREATE TYPE rca_method AS ENUM ('five_why', 'fishbone', 'other');

CREATE TABLE investigations (
  id                    UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  incident_id           UUID NOT NULL REFERENCES incidents(id) ON DELETE RESTRICT,
  investigator_id       UUID NOT NULL REFERENCES users(id),
  method                rca_method NOT NULL DEFAULT 'five_why',
  findings_text         TEXT,
  root_cause_summary    TEXT,
  alcohol_test_result   TEXT,
  witness_statement_refs TEXT[],
  completed_at          TIMESTAMPTZ,
  created_at            TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE INDEX evidence_files_incident_idx  ON evidence_files(incident_id);
CREATE INDEX investigations_incident_idx  ON investigations(incident_id);