#!/usr/bin/env bash

set -euo pipefail

# ========================================
# Source Shared Libraries
# ========================================

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]:-$0}")" && pwd)"
source "$SCRIPT_DIR/lib/config-loader.sh"
source "$SCRIPT_DIR/lib/model-router.sh"
source "$SCRIPT_DIR/../hooks/lib/project-root.sh"

PLUGIN_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
PROJECT_ROOT="$(resolve_project_root)" || {
    echo "Error: Cannot determine project root." >&2
    echo "  Set CLAUDE_PROJECT_DIR or run inside a git repository." >&2
    exit 1
}
MERGED_CONFIG="$(load_merged_config "$PLUGIN_ROOT" "$PROJECT_ROOT")"
BITLESSON_MODEL="$(get_config_value "$MERGED_CONFIG" "bitlesson_model")"
BITLESSON_MODEL="${BITLESSON_MODEL:-haiku}"
CODEX_FALLBACK_MODEL="$(get_config_value "$MERGED_CONFIG" "codex_model")"
CODEX_FALLBACK_MODEL="${CODEX_FALLBACK_MODEL:-$DEFAULT_CODEX_MODEL}"
PROVIDER_MODE="$(get_config_value "$MERGED_CONFIG" "provider_mode")"
PROVIDER_MODE="${PROVIDER_MODE:-auto}"

# Source portable timeout wrapper
source "$SCRIPT_DIR/portable-timeout.sh"

# Source shared loop library (kept for consistency with ask-codex.sh)
HOOKS_LIB_DIR="$(cd "$SCRIPT_DIR/../hooks/lib" && pwd)"
source "$HOOKS_LIB_DIR/loop-common.sh"

usage() {
    cat <<'USAGE_EOF' >&2
Usage:
  bitlesson-select.sh --task <string> --paths <comma-separated> --bitlesson-file <path>

Output (exactly):
  LESSON_IDS: <comma-separated IDs or NONE>
  RATIONALE: <one concise sentence>
USAGE_EOF
}

TASK=""
PATHS=""
BITLESSON_FILE=""

while [[ $# -gt 0 ]]; do
    case "$1" in
        -h|--help)
            usage
            exit 0
            ;;
        --task)
            TASK="${2:-}"
            shift 2
            ;;
        --paths)
            PATHS="${2:-}"
            shift 2
            ;;
        --bitlesson-file)
            BITLESSON_FILE="${2:-}"
            shift 2
            ;;
        *)
            echo "Error: Unknown argument: $1" >&2
            usage
            exit 1
            ;;
    esac
done

if [[ -z "$TASK" ]]; then
    echo "Error: --task is required and must be non-empty" >&2
    usage
    exit 1
fi

if [[ -z "$PATHS" ]]; then
    echo "Error: --paths is required and must be non-empty" >&2
    usage
    exit 1
fi

if [[ -z "$BITLESSON_FILE" ]]; then
    echo "Error: --bitlesson-file is required" >&2
    usage
    exit 1
fi

if [[ ! -f "$BITLESSON_FILE" ]]; then
    echo "Error: BitLesson file not found: $BITLESSON_FILE" >&2
    exit 1
fi

BITLESSON_CONTENT="$(cat "$BITLESSON_FILE")"
if [[ -z "$(printf '%s' "$BITLESSON_CONTENT" | tr -d ' \t\n\r')" ]]; then
    echo "Error: BitLesson file is empty (whitespace only): $BITLESSON_FILE" >&2
    exit 1
fi

if ! printf '%s\n' "$BITLESSON_CONTENT" | grep -Eq '^[[:space:]]*##[[:space:]]+Lesson:'; then
    printf 'LESSON_IDS: NONE\n'
    printf 'RATIONALE: The BitLesson file has no recorded lessons yet.\n'
    exit 0
fi

# ========================================
# Determine Provider from BITLESSON_MODEL
# ========================================

BITLESSON_PROVIDER="$(detect_provider "$BITLESSON_MODEL")"

if [[ "$PROVIDER_MODE" == "codex-only" ]] && [[ "$BITLESSON_PROVIDER" == "claude" ]]; then
    BITLESSON_MODEL="$CODEX_FALLBACK_MODEL"
    BITLESSON_PROVIDER="codex"
fi

# ========================================
# Conditional Dependency Check (with fallback)
# ========================================

if ! check_provider_dependency "$BITLESSON_PROVIDER" 2>/dev/null; then
    # Fall back to codex provider when the configured provider binary is missing
    BITLESSON_MODEL="$DEFAULT_CODEX_MODEL"
    BITLESSON_PROVIDER="codex"
    check_provider_dependency "$BITLESSON_PROVIDER"
fi

# ========================================
# Detect Project Root (for -C)
# ========================================

BITLESSON_DIR="$(cd "$(dirname "$BITLESSON_FILE")" && pwd -P)"
if git -C "$BITLESSON_DIR" rev-parse --show-toplevel &>/dev/null; then
    CODEX_PROJECT_ROOT="$(git -C "$BITLESSON_DIR" rev-parse --show-toplevel)"
else
    CODEX_PROJECT_ROOT="$BITLESSON_DIR"
fi

# ========================================
# Build Selector Prompt
# ========================================

PROMPT="$(cat <<EOF
# BitLesson Selector

You select which lessons from the configured BitLesson file (normally \`.humanize/bitlesson.md\`) must be applied for a given sub-task.

## Input

Sub-task description:
$TASK

Related file paths (comma-separated):
$PATHS

BitLesson file content:
<<<BEGIN_BITLESSON_MD
$BITLESSON_CONTENT
<<<END_BITLESSON_MD

## Decision Rules

1. Match only lessons that are directly relevant to the sub-task scope and failure mode.
2. Prefer precision over recall: do not include weakly related lessons.
3. If nothing is relevant, return \`NONE\`.
4. Use only the information in this prompt. Do not use tools, shell commands, browser access, MCP servers, or repository inspection.

## Output Format (Stable)

Return exactly two lines (no code blocks, no extra whitespace, no additional sections):

LESSON_IDS: <comma-separated lesson IDs or NONE>
RATIONALE: <one concise sentence>
EOF
)"

# ========================================
# Run Selector (Codex or Claude)
# ========================================

SELECTOR_TIMEOUT=120

run_selector() {
    local provider="$1"
    local model="$2"

    if [[ "$provider" == "codex" ]]; then
        local codex_exec_args=()
        # Probe whether the installed Codex CLI supports --disable flag
        if codex --help 2>&1 | grep -q -- '--disable'; then
            codex_exec_args+=("--disable" "hooks")
        fi
        # Probe for --skip-git-repo-check and --ephemeral support
        if codex exec --help 2>&1 | grep -q -- '--skip-git-repo-check'; then
            codex_exec_args+=("--skip-git-repo-check")
        fi
        if codex exec --help 2>&1 | grep -q -- '--ephemeral'; then
            codex_exec_args+=("--ephemeral")
        fi
        codex_exec_args+=(
            "-s" "read-only"
            "-m" "$model"
            "-c" "model_reasoning_effort=low"
            "-C" "$CODEX_PROJECT_ROOT"
        )
        printf '%s' "$PROMPT" | run_with_timeout "$SELECTOR_TIMEOUT" codex exec "${codex_exec_args[@]}" -
        return $?
    fi

    if [[ "$provider" == "claude" ]]; then
        printf '%s' "$PROMPT" | run_with_timeout "$SELECTOR_TIMEOUT" claude --print --model "$model" -
        return $?
    fi

    echo "Error: Unsupported BitLesson provider '$provider'" >&2
    return 1
}

CODEX_EXIT_CODE=0
RAW_OUTPUT="$(run_selector "$BITLESSON_PROVIDER" "$BITLESSON_MODEL" 2>&1)" || CODEX_EXIT_CODE=$?

if [[ $CODEX_EXIT_CODE -eq 124 ]]; then
    echo "Error: BitLesson selector timed out after ${SELECTOR_TIMEOUT} seconds" >&2
    exit 124
fi

if [[ $CODEX_EXIT_CODE -ne 0 ]]; then
    echo "Error: BitLesson selector failed (exit code $CODEX_EXIT_CODE)" >&2
    printf '%s\n' "$RAW_OUTPUT" >&2
    exit "$CODEX_EXIT_CODE"
fi

# ========================================
# Enforce Stable Output Format
# ========================================

LESSON_IDS_VALUE="$(
    printf '%s\n' "$RAW_OUTPUT" \
        | sed -n 's/^[[:space:]]*LESSON_IDS:[[:space:]]*//p' \
        | head -n 1 \
        | tr -d '\r' \
        | sed 's/[[:space:]]*$//'
)"

RATIONALE_VALUE="$(
    printf '%s\n' "$RAW_OUTPUT" \
        | sed -n 's/^[[:space:]]*RATIONALE:[[:space:]]*//p' \
        | head -n 1 \
        | tr -d '\r' \
        | sed 's/[[:space:]]*$//'
)"

if [[ -z "$LESSON_IDS_VALUE" || -z "$RATIONALE_VALUE" ]]; then
    echo "Error: Unexpected selector output format (expected LESSON_IDS and RATIONALE lines)" >&2
    echo "" >&2
    echo "Raw output:" >&2
    printf '%s\n' "$RAW_OUTPUT" >&2
    exit 1
fi

printf 'LESSON_IDS: %s\n' "$LESSON_IDS_VALUE"
printf 'RATIONALE: %s\n' "$RATIONALE_VALUE"