#!/usr/bin/env bash
# Test coverage collection and threshold enforcement.
#
# Runs Rust tests with llvm-cov and frontend tests with vitest --coverage.
# Reports line coverage percentages for each.
#
# Threshold: reads from COVERAGE_THRESHOLD env var, or .coverage_baseline file.
# Default: 0% (any coverage passes; baseline is written on first run).
#
# Coverage can only go up: if current coverage is above the stored baseline,
# the baseline is updated automatically.
#
# Exit codes:
#   0 — all coverage at or above threshold
#   1 — coverage below threshold

set -uo pipefail

SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
PROJECT_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
BASELINE_FILE="$PROJECT_ROOT/.coverage_baseline"

# ── Load threshold ────────────────────────────────────────────────────────────
if [ -n "${COVERAGE_THRESHOLD:-}" ]; then
    THRESHOLD="$COVERAGE_THRESHOLD"
elif [ -f "$BASELINE_FILE" ]; then
    THRESHOLD=$(cat "$BASELINE_FILE")
else
    THRESHOLD=0
fi

echo "=== Coverage threshold: ${THRESHOLD}% ==="
echo ""

PASS=true
RUST_LINE_COV=0
FRONTEND_LINE_COV=0

# ── Rust coverage ─────────────────────────────────────────────────────────────
echo "=== Running Rust tests with coverage ==="
RUST_REPORT=""
if cargo llvm-cov --version >/dev/null 2>&1; then
    RUST_REPORT=$(cargo llvm-cov \
        --manifest-path "$PROJECT_ROOT/Cargo.toml" \
        --summary-only \
        2>&1) || true
    echo "$RUST_REPORT"

    # Parse the TOTAL line: columns are space-separated with % on coverage cols.
    # Format: TOTAL <regions> <missed> <cover%> <funcs> <missed> <exec%> <lines> <missed> <cover%> ...
    # We want field 10 (lines cover %).
    RUST_RAW=$(echo "$RUST_REPORT" | awk '/^TOTAL/ { print $10 }' | tr -d '%')
    if [ -n "$RUST_RAW" ]; then
        RUST_LINE_COV="$RUST_RAW"
    fi
else
    echo "cargo-llvm-cov not available; skipping Rust coverage"
fi
echo "Rust line coverage: ${RUST_LINE_COV}%"
echo ""

# ── Frontend coverage ─────────────────────────────────────────────────────────
echo "=== Running frontend tests with coverage ==="
FRONTEND_DIR="$PROJECT_ROOT/frontend"
FRONTEND_LINE_COV=0
if [ -d "$FRONTEND_DIR" ]; then
    FRONTEND_REPORT=$(cd "$FRONTEND_DIR" && npm run test:coverage 2>&1) || true
    echo "$FRONTEND_REPORT"

    # Parse "All files" line from vitest coverage text table.
    # Format: All files | % Stmts | % Branch | % Funcs | % Lines | ...
    FRONTEND_RAW=$(echo "$FRONTEND_REPORT" | awk -F'|' '/All files/ { gsub(/ /, "", $5); print $5 }' | head -1)
    if [ -n "$FRONTEND_RAW" ]; then
        FRONTEND_LINE_COV="$FRONTEND_RAW"
    fi
else
    echo "No frontend/ directory found; skipping frontend coverage"
fi
echo "Frontend line coverage: ${FRONTEND_LINE_COV}%"
echo ""

# ── Overall (average of available measurements) ───────────────────────────────
if [ "$RUST_LINE_COV" != "0" ] && [ "$FRONTEND_LINE_COV" != "0" ]; then
    OVERALL=$(awk "BEGIN { printf \"%.1f\", ($RUST_LINE_COV + $FRONTEND_LINE_COV) / 2 }")
elif [ "$RUST_LINE_COV" != "0" ]; then
    OVERALL="$RUST_LINE_COV"
elif [ "$FRONTEND_LINE_COV" != "0" ]; then
    OVERALL="$FRONTEND_LINE_COV"
else
    OVERALL=0
fi

# ── Summary ───────────────────────────────────────────────────────────────────
echo "=== Coverage Summary ==="
echo "  Rust:     ${RUST_LINE_COV}%"
echo "  Frontend: ${FRONTEND_LINE_COV}%"
echo "  Overall:  ${OVERALL}%"
echo "  Threshold: ${THRESHOLD}%"
echo ""

# ── Threshold check ───────────────────────────────────────────────────────────
if awk "BEGIN { exit (($OVERALL + 0) < ($THRESHOLD + 0)) ? 0 : 1 }"; then
    echo "FAIL: Coverage ${OVERALL}% is below threshold ${THRESHOLD}%"
    PASS=false
else
    echo "PASS: Coverage ${OVERALL}% meets threshold ${THRESHOLD}%"
fi

# ── Update baseline when coverage improves ────────────────────────────────────
if [ "$PASS" = "true" ]; then
    STORED_BASELINE="${THRESHOLD}"
    if awk "BEGIN { exit (($OVERALL + 0) > ($STORED_BASELINE + 0)) ? 0 : 1 }"; then
        echo "${OVERALL}" > "$BASELINE_FILE"
        echo "Baseline updated: ${STORED_BASELINE}% → ${OVERALL}%"
    fi
fi

if [ "$PASS" = "false" ]; then
    exit 1
fi
