#!/bin/bash

# Generate GitHub-compatible release notes for an OBITools4 version.
#
# Usage:
#   ./release_notes.sh                 # latest version
#   ./release_notes.sh -v 4.4.15       # specific version
#   ./release_notes.sh -l              # list available versions
#   ./release_notes.sh -r              # raw commit list (no LLM)
#   ./release_notes.sh -c -v 4.4.16   # show LLM context for a version

GITHUB_REPO="metabarcoding/obitools4"
GITHUB_API="https://api.github.com/repos/${GITHUB_REPO}"
VERSION=""
LIST_VERSIONS=false
RAW_MODE=false
CONTEXT_MODE=false
LLM_MODEL="ollama:qwen3-coder-next:latest"

# ── Helpers ──────────────────────────────────────────────────────────────

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

next_patch() {
  local v="$1"
  local major minor patch
  major=$(echo "$v" | cut -d. -f1)
  minor=$(echo "$v" | cut -d. -f2)
  patch=$(echo "$v" | cut -d. -f3)
  echo "${major}.${minor}.$(( patch + 1 ))"
}

# Strip "pre-" prefix to get the bare version number for installation section
bare_version() {
  echo "$1" | sed 's/^pre-//'
}

installation_section() {
  local v
  v=$(bare_version "$1")
  cat <<INSTALL_EOF

## Installation

### Pre-built binaries

Download the appropriate archive for your system from the
[release assets](https://github.com/metabarcoding/obitools4/releases/tag/Release_${v})
and extract it:

#### Linux (AMD64)
\`\`\`bash
tar -xzf obitools4_${v}_linux_amd64.tar.gz
\`\`\`

#### Linux (ARM64)
\`\`\`bash
tar -xzf obitools4_${v}_linux_arm64.tar.gz
\`\`\`

#### macOS (Intel)
\`\`\`bash
tar -xzf obitools4_${v}_darwin_amd64.tar.gz
\`\`\`

#### macOS (Apple Silicon)
\`\`\`bash
tar -xzf obitools4_${v}_darwin_arm64.tar.gz
\`\`\`

All OBITools4 binaries are included in each archive.

### From source

You can also compile and install OBITools4 directly from source using the
installation script:

\`\`\`bash
curl -L https://raw.githubusercontent.com/metabarcoding/obitools4/master/install_obitools.sh | bash -s -- --version ${v}
\`\`\`

By default binaries are installed in \`/usr/local/bin\`. Use \`--install-dir\` to
change the destination and \`--obitools-prefix\` to add a prefix to command names:

\`\`\`bash
curl -L https://raw.githubusercontent.com/metabarcoding/obitools4/master/install_obitools.sh | \\
  bash -s -- --version ${v} --install-dir ~/local --obitools-prefix k
\`\`\`
INSTALL_EOF
}

display_help() {
  cat <<EOF
Usage: $(basename "$0") [OPTIONS]

Generate GitHub-compatible Markdown release notes for an OBITools4 version.

Options:
  -v, --version VERSION   Target version (e.g., 4.4.15). Default: latest.
  -l, --list              List all available versions and exit.
  -r, --raw               Output raw commit list without LLM summarization.
  -c, --context           Show the exact context (commits + prompt) sent to the LLM.
  -m, --model MODEL       LLM model for orla (default: $LLM_MODEL).
  -h, --help              Display this help message.

Examples:
  $(basename "$0")                  # release notes for the latest version
  $(basename "$0") -v 4.4.15       # release notes for a specific version
  $(basename "$0") -l              # list versions
  $(basename "$0") -r -v 4.4.15    # raw commit log for a version
  $(basename "$0") -c -v 4.4.16    # show LLM context for a version
EOF
}

# Fetch all Release tags from GitHub API (sorted newest first)
fetch_versions() {
  curl -sf "${GITHUB_API}/releases" \
    | grep '"tag_name":' \
    | sed -E 's/.*"tag_name": "Release_([0-9.]+)".*/\1/' \
    | sort -V -r
}

# ── Parse arguments ──────────────────────────────────────────────────────

while [ "$#" -gt 0 ]; do
  case "$1" in
    -v|--version)  VERSION="$2"; shift 2 ;;
    -l|--list)     LIST_VERSIONS=true; shift ;;
    -r|--raw)      RAW_MODE=true; shift ;;
    -c|--context)  CONTEXT_MODE=true; shift ;;
    -m|--model)    LLM_MODEL="$2"; shift 2 ;;
    -h|--help)     display_help; exit 0 ;;
    *)             die "Unsupported option: $1" ;;
  esac
done

# ── List mode ────────────────────────────────────────────────────────────

if [ "$LIST_VERSIONS" = true ]; then
  echo "Available OBITools4 versions:" >&2
  echo "==============================" >&2
  fetch_versions
  exit 0
fi

# ── Resolve versions ─────────────────────────────────────────────────────

all_versions=$(fetch_versions)
[ -z "$all_versions" ] && die "Could not fetch versions from GitHub"

if [ -z "$VERSION" ]; then
   # ── Pre-release mode: local HEAD vs latest GitHub tag ──────────────────
   PRE_RELEASE=true
   previous_tag="Release_${latest_version}"
   VERSION="pre-$(next_patch "$latest_version")"

   echo "Pre-release mode: $previous_tag -> HEAD (as $VERSION)" >&2

   # Need to be in a git repo
   if ! git rev-parse --is-inside-work-tree >/dev/null 2>&1; then
     die "Not inside a git repository. Pre-release mode requires a local git repo."
   fi

   # Check that the previous tag exists locally
   if ! git rev-parse "$previous_tag" >/dev/null 2>&1; then
     echo "Tag $previous_tag not found locally, fetching..." >&2
     git fetch --tags 2>/dev/null || true
     if ! git rev-parse "$previous_tag" >/dev/null 2>&1; then
       die "Tag $previous_tag not found locally or remotely"
     fi
   fi

  # Get local commits from the tag to HEAD (full messages)
  commit_list=$(git log --format="%h %B" "${previous_tag}..HEAD" 2>/dev/null)

   if [ -z "$commit_list" ]; then
     die "No local commits found since $previous_tag"
   fi
 else
   # ── Published release mode: between two GitHub tags ────────────────────
   PRE_RELEASE=false
   tag_name="Release_${VERSION}"

   # Verify the requested version exists
   if ! echo "$all_versions" | grep -qx "$VERSION"; then
     die "Version $VERSION not found. Use -l to list available versions."
   fi

   # Find the previous version
   previous_version=$(echo "$all_versions" | grep -A1 -x "$VERSION" | tail -1)

   if [ "$previous_version" = "$VERSION" ] || [ -z "$previous_version" ]; then
     previous_tag=""
     echo "No previous version found -- will include all commits for $tag_name" >&2
   else
     previous_tag="Release_${previous_version}"
     echo "Generating notes: $previous_tag -> $tag_name" >&2
   fi

   # Fetch commit messages between tags via GitHub compare API
   if [ -n "$previous_tag" ]; then
     commits_json=$(curl -sf "${GITHUB_API}/compare/${previous_tag}...${tag_name}")
     if [ -z "$commits_json" ]; then
       die "Could not fetch commit comparison from GitHub"
     fi
     commit_list=$(echo "$commits_json" \
      | jq -r '.commits[] | (.sha[:8] + " " + .commit.message)' 2>/dev/null)
   else
     commits_json=$(curl -sf "${GITHUB_API}/commits?sha=${tag_name}&per_page=50")
     if [ -z "$commits_json" ]; then
       die "Could not fetch commits from GitHub"
     fi
     commit_list=$(echo "$commits_json" \
      | jq -r '.[] | (.sha[:8] + " " + .commit.message)' 2>/dev/null)
   fi

   if [ -z "$commit_list" ]; then
     die "No commits found between $previous_tag and $tag_name"
   fi
fi

# ── LLM prompt (shared by context mode and summarization) ────────────────

LLM_PROMPT="Summarize the following commits into a GitHub release note for version ${VERSION}. \
Ignore commits related to version bumps, .gitignore changes, or any internal housekeeping \
that is irrelevant to end users. Describe each user-facing change precisely without exposing \
code. Eliminate redundancy. Output strictly valid JSON with no surrounding text, using this \
exact schema: {\"title\": \"<short release title>\", \"body\": \"<detailed markdown release notes>\"}"

# ── Raw mode: just output the commit list ────────────────────────────────

if [ "$RAW_MODE" = true ]; then
  echo "# Release ${VERSION}"
  echo ""
  echo "## Commits"
  echo ""
  echo "$commit_list" | while IFS= read -r line; do
    echo "- ${line}"
  done
  installation_section "$VERSION"
  exit 0
fi

# ── Context mode: show what would be sent to the LLM ────────────────────

if [ "$CONTEXT_MODE" = true ]; then
  echo "=== LLM Model ==="
  echo "$LLM_MODEL"
  echo ""
  echo "=== Prompt ==="
  echo "$LLM_PROMPT"
  echo ""
  echo "=== Stdin (commit list) ==="
  echo "$commit_list"
  exit 0
fi

# ── LLM summarization ───────────────────────────────────────────────────

if ! command -v orla >/dev/null 2>&1; then
  die "orla is required for LLM summarization. Use -r for raw output."
fi

if ! command -v jq >/dev/null 2>&1; then
  die "jq is required for JSON parsing. Use -r for raw output."
fi

echo "Summarizing with LLM ($LLM_MODEL)..." >&2

raw_output=$(echo "$commit_list" | \
  ORLA_MAX_TOOL_CALLS=50 orla agent -m "$LLM_MODEL" \
  "$LLM_PROMPT" \
  2>/dev/null) || true

if [ -z "$raw_output" ]; then
  echo "Warning: LLM returned empty output, falling back to raw mode" >&2
  exec "$0" -r -v "$VERSION"
fi

# Sanitize: extract JSON object, strip control characters
sanitized=$(echo "$raw_output" | sed -n '/^{/,/^}/p' | tr -d '\000-\011\013-\014\016-\037')

release_title=$(echo "$sanitized" | jq -r '.title // empty' 2>/dev/null)
release_body=$(echo "$sanitized" | jq -r '.body // empty' 2>/dev/null)

if [ -n "$release_title" ] && [ -n "$release_body" ]; then
  echo "# ${release_title}"
  echo ""
  echo "$release_body"
  installation_section "$VERSION"
else
  echo "Warning: JSON parsing failed, falling back to raw mode" >&2
  exec "$0" -r -v "$VERSION"
fi