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

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

# Ctrl+C: gum handles SIGINT itself and exits 130, so also handle the case where
# the signal does reach us (plain read/select fallbacks).
abort() {
    echo "Aborted." >&2
    exit 130
}
trap abort INT TERM

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

# Bail out when an interactive prompt was cancelled with Ctrl+C (gum exits 130);
# other non-zero statuses (e.g. Esc = no selection) are treated as empty input.
check_cancelled() {
    local status=$1
    [[ $status -eq 130 ]] && abort
    return 0
}

has_gum() {
    command -v gum >/dev/null 2>&1
}

# new_tempfile <var> [suffix]: create a temp file, register it for cleanup and
# store its path in <var> (no subshell, so temp_files stays in sync).
new_tempfile() {
    local f
    f=$(mktemp -t pr-create.XXXXXX)
    if [[ -n "${2:-}" ]]; then
        mv "$f" "$f$2"
        f+=$2
    fi
    temp_files+=("$f")
    printf -v "$1" '%s' "$f"
}

trim() {
    local s=$1
    s=${s#"${s%%[![:space:]]*}"}
    s=${s%"${s##*[![:space:]]}"}
    printf '%s' "$s"
}

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

Fills in every field automatically, then shows a review screen where you can
change anything before the PR is created. --yes skips the review.

Defaults:
  title      last commit subject (single conventional commit), else generated by pi
  body       generated by pi from the branch diff
  base       repo default branch
  linear     "Closes <ID>" for a ticket ID at the start of the branch name
  draft no, reviewers none, push yes

Options:
  --title <text>             PR title (conventional, e.g. "feat: ...", "fix(api): ...")
  --base <branch>            Base branch (default: repo default)
  --draft / --no-draft       Create as draft PR
  --reviewers <group|handles>  Reviewer group from config, comma separated
                             handles, or "none" (repeatable)
  --body-file <path>         Use this file as the PR body (skips generation)
  --linear <"Closes ABC-1">  Linear link line (repeatable, replaces branch detection;
                             "" = none)
  --push / --no-push         Push the branch if needed (default: push)
  --no-generate              Do not call pi for title or body
  -y, --yes                  Skip the review screen and create directly
  -h, --help                 Show this help

Title and body come from the /pr-title and /pr-body pi commands (pi-extensions
pr-create), using the "fast" chain in ~/.pi/agent/extension-models.json.
Reviewer groups are read from:
  ${GIT_PR_REVIEWERS_FILE:-${XDG_CONFIG_HOME:-~/.config}/git-pr/reviewers.conf}
EOF
}

title=""
base=""
draft="no"
reviewer_args=()
selected_reviewers=()
body_file=""
body_source="none"
linear_links=()
linear_given=0
push="yes"
generate="yes"
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)
        reviewer_args+=("$2")
        shift 2
        ;;
    --body-file)
        [[ -f $2 ]] || die "Body file not found: $2"
        # Work on a copy so edits and Linear lines never touch the caller's file.
        new_tempfile body_file .md
        cp "$2" "$body_file"
        body_source="file"
        shift 2
        ;;
    --linear)
        [[ -n $2 ]] && linear_links+=("$2")
        linear_given=1
        shift 2
        ;;
    --push)
        push="yes"
        shift
        ;;
    --no-push)
        push="no"
        shift
        ;;
    --no-generate)
        generate="no"
        shift
        ;;
    -y | --yes)
        assume_yes=1
        shift
        ;;
    -h | --help)
        usage
        exit 0
        ;;
    *)
        echo "Unknown option: $1" >&2
        usage >&2
        exit 2
        ;;
    esac
done

# --- prompts ---------------------------------------------------------------

# Echo the question/answer pair so the transcript stays visible (gum clears its
# own UI once an answer is given).
record_answer() {
    local label=$1 answer=$2
    [[ -z "$answer" ]] && answer="(empty)"
    if has_gum; then
        gum style --foreground 2 "✓ $label: $answer" >&2
    else
        printf '✓ %s: %s\n' "$label" "$answer" >&2
    fi
}

prompt_input() {
    local prompt=$1 placeholder=${2:-} initial=${3:-} value
    if has_gum; then
        value=$(gum input --width 0 --prompt "$prompt: " --value "$initial" ${placeholder:+--placeholder "$placeholder"}) || check_cancelled $?
    else
        read -r -e -i "$initial" -p "$prompt: " value || abort
    fi
    record_answer "$prompt" "$value"
    printf '%s\n' "$value"
}

prompt_menu() {
    local title=$1 choice
    shift
    if has_gum; then
        choice=$(gum choose --header "$title" --cursor "❯ " --header.foreground "#cba6f7" --header.bold --cursor.foreground "#f5c2e7" "$@") || check_cancelled $?
    else
        select choice in "$@"; do
            [[ -n "$choice" ]] && break
        done
    fi
    printf '%s\n' "$choice"
}

# Multi-select with fuzzy search; prints one selection per line.
prompt_multi() {
    local title=$1 selection answer
    shift
    [[ $# -eq 0 ]] && return
    if has_gum; then
        selection=$(gum filter --no-limit --height 15 --header "$title" --placeholder "type to search, tab to select, enter to confirm" "$@") || check_cancelled $?
    else
        read -r -p "$title (space separated, empty for none): " answer || abort
        # shellcheck disable=SC2086 # intentional word splitting
        selection=$(printf '%s\n' $answer)
    fi
    record_answer "$title" "$(printf '%s' "$selection" | tr '\n' ' ')"
    printf '%s\n' "$selection"
}

# --- reviewers -------------------------------------------------------------

reviewers_file=${GIT_PR_REVIEWERS_FILE:-${XDG_CONFIG_HOME:-$HOME/.config}/git-pr/reviewers.conf}
reviewer_group_names=()
reviewer_group_members=()
all_reviewers=()
all_reviewer_labels=()

# dedupe_list <items...>: print items once each, preserving order.
dedupe_list() {
    local out=() item existing seen
    for item in "$@"; do
        [[ -z "$item" ]] && continue
        seen=0
        for existing in "${out[@]:-}"; do
            [[ "$existing" == "$item" ]] && seen=1 && break
        done
        [[ $seen -eq 0 ]] && out+=("$item")
    done
    [[ ${#out[@]} -gt 0 ]] && printf '%s\n' "${out[@]}"
    return 0
}

# Config format (INI-ish, sections optional; default section is [people]):
#   [groups]
#   Core Network Squad = onomondo/core-network-squad
#   [people]
#   peterbornerup = Peter S. Bornerup
add_person() {
    local handle=$1 name=$2 existing
    [[ -z "$handle" ]] && return 0
    for existing in "${all_reviewers[@]:-}"; do
        [[ "$existing" == "$handle" ]] && return 0
    done
    all_reviewers+=("$handle")
    if [[ -n "$name" ]]; then
        all_reviewer_labels+=("$handle - $name")
    else
        all_reviewer_labels+=("$handle")
    fi
}

load_reviewer_config() {
    [[ -f "$reviewers_file" ]] || return 0
    local line section=people key value handle
    local handles=()
    while IFS= read -r line || [[ -n "$line" ]]; do
        line=$(trim "${line%%#*}")
        [[ -z "$line" ]] && continue
        if [[ "$line" =~ ^\[(.+)\]$ ]]; then
            section=$(printf '%s' "${BASH_REMATCH[1]}" | tr '[:upper:]' '[:lower:]')
            continue
        fi
        if [[ "$line" == *=* ]]; then
            key=$(trim "${line%%=*}")
            value=$(trim "${line#*=}")
        else
            key=$line
            value=""
        fi
        [[ -z "$key" ]] && continue
        if [[ "$section" == "groups" ]]; then
            [[ -z "$value" ]] && continue
            value=$(printf '%s' "$value" | tr -d '[:space:]')
            reviewer_group_names+=("$key")
            reviewer_group_members+=("$value")
            IFS=',' read -r -a handles <<<"$value"
            for handle in "${handles[@]}"; do
                # Team refs (org/team) are not individually selectable.
                [[ -n "$handle" && "$handle" != */* ]] && add_person "$handle" ""
            done
        else
            add_person "$key" "$value"
        fi
    done <"$reviewers_file"
}

group_members() {
    local want=$1 i
    for i in "${!reviewer_group_names[@]}"; do
        if [[ "${reviewer_group_names[$i]}" == "$want" ]]; then
            printf '%s' "${reviewer_group_members[$i]}"
            return 0
        fi
    done
    return 1
}

add_reviewers() {
    local spec=$1 members handle
    local handles=()
    [[ "$(printf '%s' "$spec" | tr '[:upper:]' '[:lower:]')" == "none" ]] && return 0
    if members=$(group_members "$spec"); then
        spec=$members
    fi
    IFS=',' read -r -a handles <<<"$spec"
    for handle in "${handles[@]}"; do
        handle=$(trim "$handle")
        [[ -n "$handle" ]] && selected_reviewers+=("$handle")
    done
    return 0
}

pick_reviewers() {
    local choices=() label group manual
    for group in "${reviewer_group_names[@]}"; do
        choices+=("Group: $group")
    done
    choices+=("${all_reviewer_labels[@]}")
    selected_reviewers=()
    while IFS= read -r label; do
        [[ -z "$label" ]] && continue
        if [[ "$label" == "Group: "* ]]; then
            add_reviewers "${label#Group: }"
        else
            # Labels look like "handle - Full Name"; keep the handle.
            selected_reviewers+=("${label%% *}")
        fi
    done < <(prompt_multi "Reviewers" "${choices[@]}")
    manual=$(prompt_input "Extra handles" "comma separated, optional")
    [[ -n "$manual" ]] && add_reviewers "$manual"
    return 0
}

reviewers_csv() {
    local out
    out=$(dedupe_list "${selected_reviewers[@]:-}" | paste -sd, -)
    printf '%s' "$out"
}

# --- title -----------------------------------------------------------------

allowed_types=(feat fix docs style refactor perf test build ci chore revert deps)
types_alt=$(
    IFS='|'
    printf '%s' "${allowed_types[*]}"
)
title_re="^(${types_alt})(\([^)]+\))?!?: .+"
loose_title_re="^(${types_alt})(\([^)]+\))?(!)?[[:space:]]+(.+)$"
title_hint="<type>[(scope)][!]: <subject>  |  types: ${allowed_types[*]}"

# Print a valid conventional title for $1 (fixing gitmoji prefixes and a missing
# colon), or fail.
normalize_title() {
    local t
    t=$(trim "$1")
    [[ "$t" =~ $title_re ]] && printf '%s\n' "$t" && return 0
    # shortcut: strips :gitmoji: codes only, not unicode emoji; extend if those show up.
    while [[ "$t" =~ ^:[a-z0-9_+-]+:[[:space:]]*(.*)$ ]]; do
        t=${BASH_REMATCH[1]}
    done
    if [[ "$t" =~ $loose_title_re ]]; then
        t="${BASH_REMATCH[1]}${BASH_REMATCH[2]}${BASH_REMATCH[3]}: ${BASH_REMATCH[4]}"
    fi
    [[ "$t" =~ $title_re ]] && printf '%s\n' "$t" && return 0
    return 1
}

# --- branch context --------------------------------------------------------

default_branch() {
    git default-branch 2>/dev/null && return 0
    gh repo view --json defaultBranchRef --jq .defaultBranchRef.name 2>/dev/null
}

resolve_base_ref() {
    local b=${1#origin/} ref
    [[ -n "$b" ]] || return 1
    for ref in "origin/$b" "$b"; do
        if git rev-parse --verify --quiet "$ref" >/dev/null; then
            printf '%s' "$ref"
            return 0
        fi
    done
    return 1
}

base_ref=""

# Resolve the base ref; generation is disabled when it cannot be resolved.
build_context() {
    base_ref=$(resolve_base_ref "${base:-$default_base}") || {
        echo "Could not resolve base '${base:-$default_base}': generation disabled." >&2
        base_ref=""
    }
    return 0
}

# Linear ticket IDs at the start of the branch or after a slash: ONO-123-x, joe/ono-123-x.
branch_linear_links() {
    local rest id
    rest=$(git branch --show-current)
    while [[ "$rest" =~ (^|/)([A-Za-z][A-Za-z0-9]{1,9}-[0-9]+)(-|/|$) ]]; do
        id=${BASH_REMATCH[2]}
        printf 'Closes %s\n' "${id^^}"
        rest=${rest#*"${BASH_REMATCH[0]}"}
    done
}

# --- pi generation ---------------------------------------------------------

# run_pi <label> <command>: run a pr-create extension generator (/pr-title,
# /pr-body) in print mode. The extension computes the diff, builds its own prompt
# with the pr/unslop skills, tries the "fast" model chain and validates output.
run_pi() {
    local label=$1 command=$2 out out_file
    [[ -n "$base_ref" ]] || return 1
    if has_gum; then
        # gum spin --show-stdout prints to the terminal instead of stdout when
        # run on a tty, so capture through a file.
        new_tempfile out_file
        # shellcheck disable=SC2016 # $1/$2 expand in the inner sh
        gum spin --title "$label..." -- sh -c 'pi -p --no-session "$1" >"$2"' _ "$command $base_ref" "$out_file" || check_cancelled $?
        out=$(<"$out_file")
        rm -f "$out_file" # run_pi runs in a subshell, so the EXIT cleanup misses it
    else
        echo "$label..." >&2
        out=$(pi -p --no-session "$command $base_ref") || true
    fi
    [[ -n "$out" ]] || return 1
    printf '%s\n' "$out"
}

generate_title() {
    [[ $generate == yes ]] || return 1
    run_pi "Generating PR title" /pr-title
}

generate_body() {
    [[ $generate == yes ]] || return 1
    local out
    out=$(run_pi "Generating PR description" /pr-body) || {
        echo "Description generation failed." >&2
        return 1
    }
    [[ -n "$body_file" ]] || new_tempfile body_file .md
    printf '%s\n' "$out" >"$body_file"
    body_source="generated"
}

# Single conventional commit: use its subject. Otherwise ask pi, falling back
# to the last commit subject.
auto_title() {
    local subject count=0
    subject=$(git log -1 --pretty=%s)
    [[ -n "$base_ref" ]] && count=$(git rev-list --count "$base_ref..HEAD")
    if [[ $count -eq 1 ]] && normalize_title "$subject"; then
        return 0
    fi
    generate_title || normalize_title "$subject" || true
}

# --- review ----------------------------------------------------------------

push_status() {
    local n
    if ! git rev-parse --verify --quiet '@{u}' >/dev/null; then
        printf '%s' "new branch"
        return
    fi
    n=$(git rev-list --count '@{u}..HEAD')
    if [[ $n -eq 0 ]]; then printf 'up to date'; else printf '%s unpushed' "$n"; fi
}

show_body() {
    [[ -s "$body_file" ]] || return 0
    if has_gum; then
        gum style --foreground "#cba6f7" --bold --margin "1 0 0 0" "── PR body ──────────────────────────────" >&2
    fi
    if command -v glow >/dev/null 2>&1; then
        glow -w 100 "$body_file" >&2
    elif has_gum; then
        gum format --type markdown <"$body_file" >&2
    else
        cat "$body_file" >&2
    fi
}

show_summary() {
    local body_info="none (gh fills from commits)" reviewers linear
    [[ -s "$body_file" ]] && body_info="$(wc -l <"$body_file" | tr -d ' ') lines, $body_source"
    reviewers=$(reviewers_csv)
    linear=$(printf '%s\n' "${linear_links[@]:-}" | paste -sd, - | sed 's/,/, /g')
    local k=$'\e[1;38;2;137;180;250m' r=$'\e[0m'
    local lines=(
        "${k}Title${r}      ${title:-(missing)}"
        "${k}Base${r}       ${base:-$default_base (default)}"
        "${k}Draft${r}      $draft"
        "${k}Reviewers${r}  ${reviewers:-none}"
        "${k}Linear${r}     ${linear:-none}"
        "${k}Body${r}       $body_info"
        "${k}Push${r}       $push ($(push_status))"
    )
    if has_gum; then
        gum style --border rounded --border-foreground "#cba6f7" --padding "0 1" --margin "1 0" "${lines[@]}" >&2
    else
        printf '%s\n' "${lines[@]}" >&2
    fi
}

edit_title() {
    local t
    t=$(prompt_input "Title" "$title_hint" "$title")
    if t=$(normalize_title "$t"); then
        title=$t
    else
        echo "Invalid title, kept the old one. Format: $title_hint" >&2
    fi
}

edit_linear() {
    local raw item
    local items=()
    raw=$(prompt_input "Linear" "Closes ABC-1, Ref ABC-2 (empty = none)" "$(printf '%s\n' "${linear_links[@]:-}" | paste -sd, - | sed 's/,/, /g')")
    linear_links=()
    IFS=',' read -r -a items <<<"$raw"
    for item in "${items[@]}"; do
        item=$(trim "$item")
        [[ -z "$item" ]] && continue
        [[ "$item" =~ ^(Closes|Ref)[[:space:]] ]] || item="Closes $item"
        linear_links+=("$item")
    done
}

review() {
    show_body
    while true; do
        show_summary
        case "$(prompt_menu "Review PR" "Create" "Edit title" "Regenerate title" "Edit body" "Regenerate body" "Base" "Toggle draft" "Reviewers" "Linear" "Cancel")" in
        Create)
            [[ -n "$title" ]] && return 0
            echo "Title is required." >&2
            ;;
        "Edit title") edit_title ;;
        "Regenerate title")
            local t
            t=$(generate_title) && title=$t
            ;;
        "Edit body")
            [[ -n "$body_file" ]] || new_tempfile body_file .md
            "${VISUAL:-${EDITOR:-nvim}}" "$body_file"
            body_source="edited"
            ;;
        "Regenerate body") generate_body && show_body ;;
        Base)
            base=$(prompt_input "Base branch" "empty = $default_base" "$base")
            build_context
            [[ "$body_source" == generated ]] && echo "Body was generated against the old base. Regenerate it if needed." >&2
            ;;
        "Toggle draft") if [[ $draft == yes ]]; then draft=no; else draft=yes; fi ;;
        Reviewers) pick_reviewers ;;
        Linear) edit_linear ;;
        *)
            echo "Cancelled." >&2
            exit 1
            ;;
        esac
    done
}

# --- create ----------------------------------------------------------------

ensure_branch_pushed() {
    if ! git rev-parse --verify --quiet '@{u}' >/dev/null; then
        [[ $push == yes ]] || die "Current branch has no upstream. Push branch first."
        git push --set-upstream origin "$(git branch --show-current)" >&2
    elif [[ $(git rev-list --count '@{u}..HEAD') -ne 0 ]]; then
        [[ $push == yes ]] || die "Current branch has unpushed commits. Push branch first."
        git push >&2
    fi
}

create_pr() {
    local reviewers pr_url edit_body_file
    ensure_branch_pushed

    if [[ -s "$body_file" && ${#linear_links[@]} -gt 0 ]]; then
        printf '\n\n%s\n' "$(printf '%s\n' "${linear_links[@]}")" >>"$body_file"
    fi

    local args=(pr create --assignee @me --title "$title" --fill)
    [[ -s "$body_file" ]] && args+=(--body-file "$body_file")
    [[ -n "$base" ]] && args+=(--base "$base")
    [[ $draft == yes ]] && args+=(--draft)
    reviewers=$(reviewers_csv)
    [[ -n "$reviewers" ]] && args+=(--reviewer "$reviewers")

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

    # No body: gh filled it from commits, so append Linear links afterwards.
    if [[ ! -s "$body_file" && ${#linear_links[@]} -gt 0 ]]; then
        new_tempfile edit_body_file .md
        gh pr view "$pr_url" --json body --jq '.body' >"$edit_body_file"
        printf '\n\n%s\n' "$(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
}

# --- main ------------------------------------------------------------------

git rev-parse --is-inside-work-tree >/dev/null 2>&1 || die "Not inside a git repository."

load_reviewer_config
for spec in "${reviewer_args[@]}"; do
    add_reviewers "$spec"
done

if [[ -n "$title" ]]; then
    title=$(normalize_title "$title") || die "Invalid PR title. Format: $title_hint"
fi

if [[ $linear_given -eq 0 ]]; then
    while IFS= read -r link; do
        linear_links+=("$link")
    done < <(branch_linear_links)
fi

default_base=$(default_branch || true)
build_context

[[ -z "$title" ]] && title=$(auto_title)
[[ -z "$body_file" ]] && { generate_body || true; }

if [[ $assume_yes -eq 1 ]]; then
    [[ -n "$title" ]] || die "Could not derive a PR title. Pass --title."
else
    review
fi

create_pr