#!/usr/bin/env bash
set -euo pipefail

# Rebuild the AlphaX volume DB from a database file placed in the project root.
#
# This is different from a raw copy:
# - it creates a brand-new clean SQLite DB
# - it recreates schema from the root DB
# - it copies readable table rows into the clean DB
# - it can salvage partial data from a DB that fails integrity_check
#
# Server usage:
#   bash scripts/rebuild_volume_db_from_root_db.sh
#
# Defaults:
#   source: ./altcoin_monitor.db
#   target: ./data/altcoin_monitor.db
#
# Overrides:
#   ROOT_DB=./backup.db bash scripts/rebuild_volume_db_from_root_db.sh
#   STRICT=1 bash scripts/rebuild_volume_db_from_root_db.sh   # fail if any table/row cannot be copied
#   RESTART=0 bash scripts/rebuild_volume_db_from_root_db.sh

ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
cd "$ROOT_DIR"

COMPOSE_CMD="${COMPOSE_CMD:-docker compose}"
ROOT_DB="${ROOT_DB:-altcoin_monitor.db}"
TARGET_DB="${TARGET_DB:-data/altcoin_monitor.db}"
BACKUP_DIR="${BACKUP_DIR:-data/backups}"
RESTART="${RESTART:-1}"
STRICT="${STRICT:-0}"
WEB_SERVICE="${WEB_SERVICE:-alphax-web}"
SCHEDULER_SERVICE="${SCHEDULER_SERVICE:-alphax-scheduler}"

compose() {
  ${COMPOSE_CMD} "$@"
}

info() {
  echo "[rebuild-db] $*"
}

die() {
  echo "ERROR: $*" >&2
  exit 1
}

service_exists() {
  compose config --services 2>/dev/null | grep -qx "$1"
}

[ -f "$ROOT_DB" ] || die "root database not found: $ROOT_DIR/$ROOT_DB"
[ -s "$ROOT_DB" ] || die "root database is empty: $ROOT_DIR/$ROOT_DB"
command -v python3 >/dev/null 2>&1 || die "python3 is required on the server"

mkdir -p "$(dirname "$TARGET_DB")" "$BACKUP_DIR"

STAMP="$(date +%Y%m%d_%H%M%S)"
TEMP_DB="${BACKUP_DIR}/altcoin_monitor.rebuilt_from_root.${STAMP}.tmp.db"
REPORT_FILE="${BACKUP_DIR}/altcoin_monitor.rebuild_report.${STAMP}.json"

info "source root db: $ROOT_DIR/$ROOT_DB"
info "target volume db: $ROOT_DIR/$TARGET_DB"
info "root db candidates:"
ls -lh "$ROOT_DB"* 2>/dev/null || true

if [ "$RESTART" = "1" ]; then
  info "stopping compose services before replacing SQLite DB"
  if service_exists "$SCHEDULER_SERVICE"; then
    compose stop "$SCHEDULER_SERVICE" >/dev/null 2>&1 || true
  fi
  if service_exists "$WEB_SERVICE"; then
    compose stop "$WEB_SERVICE" >/dev/null 2>&1 || true
  fi
fi

info "rebuilding a clean SQLite DB from readable source data"
ROOT_DB="$ROOT_DB" TEMP_DB="$TEMP_DB" REPORT_FILE="$REPORT_FILE" STRICT="$STRICT" python3 - <<'PY'
import json
import os
import sqlite3
import sys
import traceback

src_path = os.environ["ROOT_DB"]
dst_path = os.environ["TEMP_DB"]
report_file = os.environ["REPORT_FILE"]
strict = os.environ.get("STRICT") == "1"

for path in (dst_path, dst_path + "-wal", dst_path + "-shm"):
    try:
        os.remove(path)
    except FileNotFoundError:
        pass

report = {
    "source": src_path,
    "target_temp": dst_path,
    "strict": strict,
    "source_integrity": None,
    "target_integrity": None,
    "tables": [],
    "schema_errors": [],
    "index_errors": [],
    "fatal": None,
}

def quote_ident(name: str) -> str:
    return '"' + str(name).replace('"', '""') + '"'

def record_table(name, copied=0, skipped=0, status="ok", error=""):
    report["tables"].append({
        "table": name,
        "copied_rows": int(copied),
        "skipped_rows": int(skipped),
        "status": status,
        "error": str(error)[:2000],
    })

def write_report():
    with open(report_file, "w", encoding="utf-8") as f:
        json.dump(report, f, ensure_ascii=False, indent=2)

try:
    src = sqlite3.connect(f"file:{src_path}?mode=ro", uri=True, timeout=30)
    src.row_factory = sqlite3.Row
    dst = sqlite3.connect(dst_path, timeout=30)
    dst.row_factory = sqlite3.Row
    dst.execute("PRAGMA foreign_keys=OFF")
    dst.execute("PRAGMA journal_mode=DELETE")
    dst.execute("PRAGMA synchronous=OFF")

    try:
        report["source_integrity"] = src.execute("PRAGMA integrity_check").fetchone()[0]
    except Exception as exc:
        report["source_integrity"] = f"failed: {exc}"

    try:
        objects = src.execute("""
            SELECT type, name, tbl_name, sql
            FROM sqlite_master
            WHERE sql IS NOT NULL
              AND name NOT LIKE 'sqlite_autoindex%'
            ORDER BY CASE type WHEN 'table' THEN 0 WHEN 'index' THEN 1 WHEN 'trigger' THEN 2 ELSE 3 END, name
        """).fetchall()
    except Exception as exc:
        report["fatal"] = f"cannot read sqlite_master: {exc}"
        write_report()
        raise SystemExit(report["fatal"])

    table_objects = [
        dict(row) for row in objects
        if row["type"] == "table" and not str(row["name"]).startswith("sqlite_")
    ]
    late_objects = [
        dict(row) for row in objects
        if row["type"] in ("index", "trigger", "view") and not str(row["name"]).startswith("sqlite_")
    ]

    for obj in table_objects:
        try:
            dst.execute(obj["sql"])
        except Exception as exc:
            report["schema_errors"].append({"object": obj["name"], "error": str(exc)})
            if strict:
                raise

    dst.commit()

    for obj in table_objects:
        table = obj["name"]
        copied = 0
        skipped = 0
        try:
            cols = [row["name"] for row in src.execute(f"PRAGMA table_info({quote_ident(table)})").fetchall()]
            if not cols:
                record_table(table, copied, skipped, "skipped", "no columns")
                continue
            col_sql = ", ".join(quote_ident(c) for c in cols)
            placeholders = ", ".join("?" for _ in cols)
            insert_sql = f"INSERT INTO {quote_ident(table)} ({col_sql}) VALUES ({placeholders})"

            rowid_available = False
            try:
                src.execute(f"SELECT rowid FROM {quote_ident(table)} LIMIT 1").fetchone()
                rowid_available = True
            except Exception:
                rowid_available = False

            if rowid_available:
                bounds = src.execute(f"SELECT min(rowid), max(rowid) FROM {quote_ident(table)}").fetchone()
                min_id, max_id = bounds[0], bounds[1]
                if min_id is None or max_id is None:
                    record_table(table, 0, 0, "ok")
                    continue
                chunk = 1000
                current = int(min_id)
                max_id = int(max_id)
                while current <= max_id:
                    end = min(current + chunk - 1, max_id)
                    try:
                        rows = src.execute(
                            f"SELECT {col_sql} FROM {quote_ident(table)} WHERE rowid BETWEEN ? AND ? ORDER BY rowid",
                            (current, end),
                        ).fetchall()
                        dst.executemany(insert_sql, [tuple(row[c] for c in cols) for row in rows])
                        copied += len(rows)
                    except Exception as chunk_exc:
                        for rowid in range(current, end + 1):
                            try:
                                row = src.execute(
                                    f"SELECT {col_sql} FROM {quote_ident(table)} WHERE rowid=?",
                                    (rowid,),
                                ).fetchone()
                                if row is None:
                                    continue
                                dst.execute(insert_sql, tuple(row[c] for c in cols))
                                copied += 1
                            except Exception:
                                skipped += 1
                        if strict and skipped:
                            raise chunk_exc
                    current = end + 1
            else:
                # Fallback for WITHOUT ROWID tables. If a malformed page breaks the
                # full scan, the whole table may be skipped.
                rows = src.execute(f"SELECT {col_sql} FROM {quote_ident(table)}").fetchall()
                dst.executemany(insert_sql, [tuple(row[c] for c in cols) for row in rows])
                copied += len(rows)

            dst.commit()
            status = "partial" if skipped else "ok"
            record_table(table, copied, skipped, status)
        except Exception as exc:
            dst.rollback()
            record_table(table, copied, skipped, "failed", exc)
            if strict:
                raise

    for obj in late_objects:
        try:
            dst.execute(obj["sql"])
        except Exception as exc:
            report["index_errors"].append({"object": obj["name"], "type": obj["type"], "error": str(exc)})
            if strict:
                raise

    dst.commit()

    try:
        report["target_integrity"] = dst.execute("PRAGMA integrity_check").fetchone()[0]
    except Exception as exc:
        report["target_integrity"] = f"failed: {exc}"

    dst.close()
    src.close()
    write_report()

    if report["target_integrity"] != "ok":
        raise SystemExit(f"rebuilt target integrity_check failed: {report['target_integrity']}")
    if strict:
        bad = [t for t in report["tables"] if t["status"] != "ok"]
        if bad or report["schema_errors"] or report["index_errors"]:
            raise SystemExit("strict rebuild failed; see report")

    print(json.dumps({
        "source_integrity": report["source_integrity"],
        "target_integrity": report["target_integrity"],
        "tables": len(report["tables"]),
        "copied_rows": sum(t["copied_rows"] for t in report["tables"]),
        "skipped_rows": sum(t["skipped_rows"] for t in report["tables"]),
        "report": report_file,
    }, ensure_ascii=False))
except Exception as exc:
    report["fatal"] = f"{exc}\n{traceback.format_exc()}"
    write_report()
    raise
PY

if [ -e "$TARGET_DB" ]; then
  OLD_BACKUP="${BACKUP_DIR}/altcoin_monitor.volume_before_rebuild.${STAMP}.db"
  info "backing up old volume db to $OLD_BACKUP"
  cp -p "$TARGET_DB" "$OLD_BACKUP"
fi

for sidecar in "${TARGET_DB}-wal" "${TARGET_DB}-shm"; do
  if [ -e "$sidecar" ]; then
    sidecar_backup="${BACKUP_DIR}/$(basename "$sidecar").volume_before_rebuild.${STAMP}"
    info "moving old sidecar $sidecar to $sidecar_backup"
    mv "$sidecar" "$sidecar_backup"
  fi
done

info "installing rebuilt db into volume path"
mv "$TEMP_DB" "$TARGET_DB"
chmod 664 "$TARGET_DB" || true

info "final integrity check"
HOST_DB="$TARGET_DB" python3 - <<'PY'
import os
import sqlite3

db = os.environ["HOST_DB"]
conn = sqlite3.connect(f"file:{db}?mode=ro", uri=True, timeout=30)
result = conn.execute("PRAGMA integrity_check").fetchone()[0]
tables = conn.execute("SELECT COUNT(*) FROM sqlite_master WHERE type='table'").fetchone()[0]
conn.close()
if result != "ok":
    raise SystemExit(f"integrity_check failed: {result}")
print(f"integrity_check=ok tables={tables} db={db}")
PY

if [ "$RESTART" = "1" ]; then
  info "starting compose services"
  if service_exists "$WEB_SERVICE"; then
    compose up -d "$WEB_SERVICE"
  fi
  if service_exists "$SCHEDULER_SERVICE"; then
    compose up -d "$SCHEDULER_SERVICE"
  fi
fi

info "done"
info "system database path: $ROOT_DIR/$TARGET_DB"
info "rebuild report: $ROOT_DIR/$REPORT_FILE"