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

temp_files=()
cleanup() {
    rm -f "${temp_files[@]}"
}
trap cleanup EXIT

# Create a temp file that ends in .md so editors detect markdown.
new_md_tempfile() {
    local f
    f=$(mktemp -t pr-description.XXXXXX)
    mv "$f" "$f.md"
    printf '%s.md' "$f"
}

usage() {
    cat <<'EOF'
Usage: pr-create [options]

All options are optional. Anything not provided is asked for interactively
(unless --yes is set, in which case sensible defaults are used).

Options:
  --title <text>             PR title (must start with a conventional type,
                             e.g. "feat: ...", "fix(api): ...")
  --base <branch>            Base branch ("" = repo default)
  --draft / --no-draft       Create as draft PR
  --reviewers <default|cns>  Reviewer set
  --generate-description     Generate PR body with pi
  --no-generate-description  Skip body generation
  --body-file <path>         Use this file as the PR body (skips generation)
  --linear <"Closes ABC-1">  Add a Linear link line (repeatable)
  --edit / --no-edit         Open body in $EDITOR before creating
  --push / --no-push         Auto-confirm pushing the branch if needed
  -y, --yes                  Non-interactive: defaults for anything unspecified
  -h, --help                 Show this help
EOF
}

# Defaults for --yes mode.
title=""
base=""
draft=""     # "yes" | "no" | ""
reviewers="" # "default" | "cns" | ""
gen_desc=""  # "yes" | "no" | ""
body_file=""
edit_desc=""   # "yes" | "no" | ""
push_choice="" # "yes" | "no" | ""
linear_links=()
assume_yes=0

while [[ $# -gt 0 ]]; do
    case "$1" in
    --title)
        title=$2
        shift 2
        ;;
    --base)
        base=$2
        shift 2
        ;;
    --draft)
        draft="yes"
        shift
        ;;
    --no-draft)
        draft="no"
        shift
        ;;
    --reviewers)
        reviewers=$(printf '%s' "$2" | tr '[:upper:]' '[:lower:]')
        shift 2
        ;;
    --generate-description)
        gen_desc="yes"
        shift
        ;;
    --no-generate-description)
        gen_desc="no"
        shift
        ;;
    --body-file)
        body_file=$2
        gen_desc="no"
        shift 2
        ;;
    --linear)
        linear_links+=("$2")
        shift 2
        ;;
    --edit)
        edit_desc="yes"
        shift
        ;;
    --no-edit)
        edit_desc="no"
        shift
        ;;
    --push)
        push_choice="yes"
        shift
        ;;
    --no-push)
        push_choice="no"
        shift
        ;;
    -y | --yes)
        assume_yes=1
        shift
        ;;
    -h | --help)
        usage
        exit 0
        ;;
    *)
        echo "Unknown option: $1" >&2
        usage >&2
        exit 2
        ;;
    esac
done

prompt_input() {
    local prompt=$1
    if [[ $assume_yes -eq 1 ]]; then
        printf ''
        return
    fi
    if command -v gum >/dev/null 2>&1; then
        gum input --prompt "$prompt: "
    else
        local value
        read -r -p "$prompt: " value
        printf '%s\n' "$value"
    fi
}

prompt_menu() {
    local title=$1
    shift
    if [[ $assume_yes -eq 1 ]]; then
        printf '%s\n' "$1"
        return
    fi
    if command -v gum >/dev/null 2>&1; then
        gum choose --header "$title" "$@"
    else
        local choice
        select choice in "$@"; do
            [[ -n "$choice" ]] && printf '%s\n' "$choice" && break
        done
    fi
}

# Normalize a yes/no value (case-insensitive) to "Yes"/"No"; empty stays empty.
normalize_yn() {
    case "$(printf '%s' "$1" | tr '[:upper:]' '[:lower:]')" in
    yes | y | true | 1) printf 'Yes' ;;
    no | n | false | 0) printf 'No' ;;
    *) printf '' ;;
    esac
}

generate_pr_description() {
    local body_file=$1
    local prompt_file
    prompt_file=$(mktemp)
    temp_files+=("$prompt_file")

    cat >"$prompt_file" <<'EOF'
Use the humanizer skill's audit loop internally to self-check the prose, then return ONLY the final result. Do not output the draft, the "still-AI" bullets, or any summary of changes — output only the final PR body, nothing else.

Generate a short GitHub pull request description for the current branch.

Requirements:
- Concise and natural.
- Summarize actual code/config changes in this PR.
- Start directly with the bullets. No summary or intro sentence; the title is a separate field.
- Prefer 2-4 bullets.
- Do not invent details.
- Do not include Linear ticket lines.
- Output only the final PR description body.
EOF

    local prompt
    prompt=$(cat "$prompt_file")
    local models=(anthropic-extra/claude-opus-4-8 anthropic/claude-opus-4-8)
    local model
    for model in "${models[@]}"; do
        if command -v gum >/dev/null 2>&1 && [[ $assume_yes -eq 0 ]]; then
            gum spin --title "Generating PR description with pi ($model)..." -- pi -p --no-session --model "$model" --thinking off "$prompt" >"$body_file"
        else
            echo "Generating PR description with pi ($model)..." >&2
            pi -p --no-session --model "$model" --thinking off "$prompt" >"$body_file"
        fi
        [[ -s $body_file ]] && return 0
    done
    return 1
}

edit_pr_description() {
    local body_file=$1
    local editor=${EDITOR:-vi}
    "$editor" "$body_file"
}

ensure_branch_pushed() {
    local choice
    if ! git rev-parse --verify --quiet '@{u}' >/dev/null; then
        choice=$(normalize_yn "$push_choice")
        [[ -z "$choice" ]] && choice=$(prompt_menu "Current branch has no upstream. Push branch now?" "Yes" "No")
        if [[ "$choice" != "Yes" ]]; then
            echo "Current branch has no upstream. Push branch first." >&2
            exit 1
        fi
        git push --set-upstream origin "$(git branch --show-current)"
        return
    fi

    local unpushed
    unpushed=$(git rev-list --count '@{u}..HEAD')
    if [[ "$unpushed" -ne 0 ]]; then
        choice=$(normalize_yn "$push_choice")
        [[ -z "$choice" ]] && choice=$(prompt_menu "Current branch has $unpushed unpushed commit(s). Push branch now?" "Yes" "No")
        if [[ "$choice" != "Yes" ]]; then
            echo "Current branch has $unpushed unpushed commit(s). Push branch first." >&2
            exit 1
        fi
        git push
    fi
}

ensure_branch_pushed

# Conventional commit types allowed in PR titles.
allowed_types=(feat fix docs style refactor perf test build ci chore revert deps)

validate_title() {
    local t=$1
    # Match: type(optional-scope)!?: subject
    local re='^(feat|fix|docs|style|refactor|perf|test|build|ci|chore|revert|deps)(\([^)]+\))?!?: .+'
    [[ "$t" =~ $re ]]
}

title_hint="format: <type>[(scope)]: <subject>  |  types: ${allowed_types[*]}"

if [[ -n "$title" ]] && ! validate_title "$title"; then
    echo "Invalid PR title: '$title'" >&2
    echo "$title_hint" >&2
    exit 1
fi

while [[ -z "$title" ]]; do
    title=$(prompt_input "Pull Request Title ($title_hint)")
    if [[ -z "$title" ]]; then
        echo "PR title is required." >&2
        [[ $assume_yes -eq 1 ]] && exit 1
        continue
    fi
    if ! validate_title "$title"; then
        echo "Invalid title. $title_hint" >&2
        [[ $assume_yes -eq 1 ]] && exit 1
        title=""
    fi
done

# Only prompt for base if user did not pass --base at all (empty is a valid explicit value when --yes).
if [[ -z "$base" && $assume_yes -eq 0 ]]; then
    # Allow an empty answer to mean "default branch".
    base=$(prompt_input "Base Branch (leave empty for default branch)")
fi

draft_norm=$(normalize_yn "$draft")
[[ -z "$draft_norm" ]] && draft_norm=$(prompt_menu "Create as draft PR?" "No" "Yes")

if [[ -z "$reviewers" ]]; then
    reviewer_choice=$(prompt_menu "Add Reviewers" "Default" "CNS")
else
    case "$reviewers" in
    default) reviewer_choice="Default" ;;
    cns) reviewer_choice="CNS" ;;
    *)
        echo "Unknown --reviewers value: $reviewers (expected default|cns)" >&2
        exit 2
        ;;
    esac
fi

if [[ -z "$body_file" ]]; then
    gen_norm=$(normalize_yn "$gen_desc")
    [[ -z "$gen_norm" ]] && gen_norm=$(prompt_menu "Generate PR description with pi?" "No" "Yes")
    if [[ "$gen_norm" == "Yes" ]]; then
        body_file=$(new_md_tempfile)
        temp_files+=("$body_file")
        generate_pr_description "$body_file"
    fi
fi

# Interactive Linear collection only when no --linear flags were passed and not --yes.
if [[ ${#linear_links[@]} -eq 0 && $assume_yes -eq 0 ]]; then
    add_linear=$(prompt_menu "Any Linear ticket(s) linked to this PR?" "No" "Yes")
    while [[ "$add_linear" == "Yes" ]]; do
        linear_ticket=$(prompt_input "Linear ticket ID (example: ABC-123)")
        linear_relation=$(prompt_menu "Relationship for $linear_ticket" "Closes" "Ref")
        if [[ -n "$linear_ticket" ]]; then
            linear_links+=("$linear_relation $linear_ticket")
        fi
        add_linear=$(prompt_menu "Add another Linear ticket?" "No" "Yes")
    done
fi

linear_appended=0
append_linear_links() {
    {
        printf '\n\n'
        printf '%s\n' "${linear_links[@]}"
    } >>"$1"
    linear_appended=1
}

edit_norm=$(normalize_yn "$edit_desc")
[[ -z "$edit_norm" ]] && edit_norm=$(prompt_menu "Open PR description in \$EDITOR before creating PR?" "No" "Yes")
if [[ "$edit_norm" == "Yes" ]]; then
    if [[ -z "$body_file" ]]; then
        body_file=$(new_md_tempfile)
        temp_files+=("$body_file")
    fi
    # Append Linear links before editing so they are part of the description the
    # user customizes (and are not lost when a fresh body file is edited).
    [[ ${#linear_links[@]} -gt 0 ]] && append_linear_links "$body_file"
    edit_pr_description "$body_file"
fi

# Append Linear links if we have a body file and haven't done so already.
if [[ $linear_appended -eq 0 && -n "$body_file" && ${#linear_links[@]} -gt 0 ]]; then
    append_linear_links "$body_file"
fi

args=(pr create --assignee @me --title "$title" --fill)

[[ -n "$body_file" ]] && args+=(--body-file "$body_file")
[[ -n "$base" ]] && args+=(--base "$base")
[[ "$draft_norm" == "Yes" ]] && args+=(--draft)
[[ "$reviewer_choice" == "CNS" ]] && args+=(--reviewer "peterbornerup,farhadh,jdejnek,finoutlook,befe-oh-no")

pr_url=$(gh "${args[@]}")
printf '%s\n' "$pr_url"

# If we created the PR without a body but have Linear links, append them after creation.
if [[ -z "$body_file" && ${#linear_links[@]} -gt 0 ]]; then
    edit_body_file=$(new_md_tempfile)
    temp_files+=("$edit_body_file")

    gh pr view "$pr_url" --json body --jq '.body' >"$edit_body_file"
    {
        printf '\n\n'
        printf '%s\n' "${linear_links[@]}"
    } >>"$edit_body_file"

    gh pr edit "$pr_url" --body-file "$edit_body_file" >/dev/null
    echo "Added Linear links to PR description." >&2
fi