#!/usr/bin/env bash
# sync-pull.sh — Import a git bundle from the shared folder into the current repo.
#
# Usage:  ./sync-pull.sh [<share-dir>]
# Default share dir: $SYNC_SHARE or ~/fifiletrans
#
# The script lists available bundles for this repo, lets you choose one,
# fetches all branches from it into refs/sync/incoming/<branch>, shows
# what's new, and offers to merge or rebase each branch.

set -euo pipefail

# ── Config ────────────────────────────────────────────────────────────────────
SHARE_DIR="${1:-${SYNC_SHARE:-$HOME/fifiletrans}}"

# ── Sanity checks ─────────────────────────────────────────────────────────────
if ! git rev-parse --git-dir &>/dev/null; then
    echo "ERROR: Not inside a git repository." >&2
    exit 1
fi

if [ ! -d "$SHARE_DIR" ]; then
    echo "ERROR: Share directory not found: $SHARE_DIR" >&2
    exit 1
fi

REPO_ROOT=$(git rev-parse --show-toplevel)
REPO_NAME=$(basename "$REPO_ROOT")

# ── Find bundles for this repo ────────────────────────────────────────────────
BUNDLES=()
while IFS= read -r f; do
    BUNDLES+=("$f")
done < <(find "$SHARE_DIR" -maxdepth 1 -name "${REPO_NAME}-from-*.bundle" | sort)

if [ ${#BUNDLES[@]} -eq 0 ]; then
    echo "No bundles found for repo '$REPO_NAME' in $SHARE_DIR"
    echo "  (looking for: ${REPO_NAME}-from-*.bundle)"
    exit 0
fi

# ── Let user pick a bundle ─────────────────────────────────────────────────────
echo "Available bundles for '$REPO_NAME':"
echo ""
for i in "${!BUNDLES[@]}"; do
    b="${BUNDLES[$i]}"
    size=$(du -sh "$b" | cut -f1)
    name=$(basename "$b")
    echo "  [$((i+1))] $name ($size)"
done
echo ""

# Default: newest bundle (last in sorted list)
DEFAULT=${#BUNDLES[@]}
read -rp "Pick bundle [1-${#BUNDLES[@]}, default $DEFAULT]: " CHOICE
CHOICE="${CHOICE:-$DEFAULT}"

if ! [[ "$CHOICE" =~ ^[0-9]+$ ]] || [ "$CHOICE" -lt 1 ] || [ "$CHOICE" -gt "${#BUNDLES[@]}" ]; then
    echo "Invalid choice." >&2
    exit 1
fi

BUNDLE_PATH="${BUNDLES[$((CHOICE-1))]}"
BUNDLE_NAME=$(basename "$BUNDLE_PATH")
echo ""
echo "Using: $BUNDLE_NAME"

# ── Verify the bundle ──────────────────────────────────────────────────────────
echo ""
echo "Verifying bundle..."
if ! git bundle verify "$BUNDLE_PATH"; then
    echo ""
    echo "ERROR: Bundle verification failed." >&2
    echo "This usually means the bundle is incremental and your repo is missing" >&2
    echo "the prerequisite commits. Make sure you have applied earlier bundles first." >&2
    exit 1
fi

# ── List refs in bundle ────────────────────────────────────────────────────────
echo ""
echo "Branches in bundle:"
BUNDLE_REFS=()
while IFS= read -r line; do
    ref=$(echo "$line" | awk '{print $2}')
    BUNDLE_REFS+=("$ref")
    branch="${ref#refs/heads/}"
    echo "  $branch"
done < <(git bundle list-heads "$BUNDLE_PATH" | grep 'refs/heads/')

if [ ${#BUNDLE_REFS[@]} -eq 0 ]; then
    echo "No branch refs found in bundle." >&2
    exit 1
fi

# ── Fetch each branch into refs/sync/incoming/<branch> ────────────────────────
echo ""
echo "Fetching..."
INCOMING_BRANCHES=()
for ref in "${BUNDLE_REFS[@]}"; do
    branch="${ref#refs/heads/}"
    incoming_ref="refs/sync/incoming/${branch}"
    git fetch "$BUNDLE_PATH" "${ref}:${incoming_ref}"
    INCOMING_BRANCHES+=("$branch")
    echo "  Fetched: $branch -> $incoming_ref"
done

# ── Show what's new per branch ────────────────────────────────────────────────
echo ""
echo "── New commits ──────────────────────────────────────────────────────────"
for branch in "${INCOMING_BRANCHES[@]}"; do
    incoming_ref="refs/sync/incoming/${branch}"
    if git rev-parse --verify "$branch" &>/dev/null; then
        # Branch exists locally
        ahead=$(git log --oneline "${branch}..${incoming_ref}" | wc -l)
        behind=$(git log --oneline "${incoming_ref}..${branch}" | wc -l)
        if [ "$ahead" -eq 0 ]; then
            echo "  $branch: already up to date"
            continue
        fi
        echo "  $branch: $ahead new commit(s) incoming, $behind local-only commit(s)"
        git log --oneline "${branch}..${incoming_ref}" | sed 's/^/    + /'
        if [ "$behind" -gt 0 ]; then
            echo "  (your local commits not in bundle:)"
            git log --oneline "${incoming_ref}..${branch}" | sed 's/^/    * /'
        fi
    else
        n=$(git log --oneline "${incoming_ref}" | wc -l)
        echo "  $branch: new branch with $n commit(s)"
        git log --oneline "${incoming_ref}" | head -10 | sed 's/^/    + /'
    fi
done
echo ""

# ── Integrate each branch ─────────────────────────────────────────────────────
CURRENT_BRANCH=$(git branch --show-current)

for branch in "${INCOMING_BRANCHES[@]}"; do
    incoming_ref="refs/sync/incoming/${branch}"

    if ! git rev-parse --verify "$branch" &>/dev/null; then
        # New branch — just create it
        read -rp "Create new local branch '$branch' from bundle? [Y/n] " ans
        ans="${ans:-Y}"
        if [[ "$ans" =~ ^[Yy] ]]; then
            git branch "$branch" "$incoming_ref"
            echo "  Created branch '$branch'"
        fi
        continue
    fi

    ahead=$(git log --oneline "${branch}..${incoming_ref}" | wc -l)
    if [ "$ahead" -eq 0 ]; then
        continue  # Nothing to do
    fi

    behind=$(git log --oneline "${incoming_ref}..${branch}" | wc -l)

    echo "── Integrating: $branch ─────────────────────────────────────────────"

    if [ "$behind" -eq 0 ]; then
        # Fast-forward possible
        echo "  Fast-forward possible."
        read -rp "  Fast-forward '$branch'? [Y/n] " ans
        ans="${ans:-Y}"
        if [[ "$ans" =~ ^[Yy] ]]; then
            # Switch to branch if needed
            if [ "$CURRENT_BRANCH" != "$branch" ]; then
                git checkout "$branch"
                CURRENT_BRANCH="$branch"
            fi
            git merge --ff-only "$incoming_ref"
            echo "  Done."
        fi
    else
        # Diverged — offer merge or rebase
        echo "  Branches have diverged (you have $behind local commit(s))."
        echo "  Options:"
        echo "    [m] merge   — creates a merge commit"
        echo "    [r] rebase  — replays your commits on top of incoming"
        echo "    [s] skip    — leave for manual handling"
        read -rp "  Choice [m/r/s, default s]: " ans
        ans="${ans:-s}"
        case "$ans" in
            m|M)
                if [ "$CURRENT_BRANCH" != "$branch" ]; then
                    git checkout "$branch"
                    CURRENT_BRANCH="$branch"
                fi
                git merge "$incoming_ref" --no-edit
                echo "  Merged."
                ;;
            r|R)
                if [ "$CURRENT_BRANCH" != "$branch" ]; then
                    git checkout "$branch"
                    CURRENT_BRANCH="$branch"
                fi
                git rebase "$incoming_ref"
                echo "  Rebased."
                ;;
            *)
                echo "  Skipped. Run manually:"
                echo "    git checkout $branch && git merge refs/sync/incoming/$branch"
                ;;
        esac
    fi
done

echo ""
echo "Import complete."
echo ""
echo "Tip: The fetched commits remain in refs/sync/incoming/<branch> until"
echo "the next sync-pull run. You can inspect them anytime with:"
echo "  git log refs/sync/incoming/<branch>"