#!/bin/bash
# download_lidar.sh — Téléchargement de fichiers LiDAR HD depuis l'IGN
#
# Usage:
#   ./download_lidar.sh LHD_FXX_1049_6895_PTS_LAMB93_IGN69.copc.laz
#   ./download_lidar.sh 1049_6895
#   ./download_lidar.sh 1049_6895 1029_6884
#   ./download_lidar.sh --list-zones
#   ./download_lidar.sh --search 1049
#   ./download_lidar.sh --zone RE --output input/
#   ./download_lidar.sh --zone RE --dry-run
#
# L'API IGN expose les fichiers organisés par zones (RE, SE, AE, etc.)
# Le script cherche automatiquement dans quelle zone se trouve chaque tuile.

set -euo pipefail

BASE_URL="https://data.geopf.fr/telechargement/download/LiDARHD-NUALID"
API_URL="https://data.geopf.fr/telechargement/resource/LiDARHD-NUALID"
OUTPUT_DIR="${OUTPUT_DIR:-.}"

# Colors
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
CYAN='\033[0;36m'
NC='\033[0m'

log_info()  { echo -e "${CYAN}[INFO]${NC} $*"; }
log_ok()    { echo -e "${GREEN}[OK]${NC} $*"; }
log_warn()  { echo -e "${YELLOW}[WARN]${NC} $*"; }
log_err()   { echo -e "${RED}[ERR]${NC} $*"; }

# Normalize a tile identifier to a full filename
# Supports: "1049_6895", "LHD_FXX_1049_6895_PTS_LAMB93_IGN69", "LHD_FXX_1049_6895_PTS_LAMB93_IGN69.copc.laz"
normalize_name() {
    local input="$1"
    # If it's already a full filename, return as-is
    if [[ "$input" == LHD_FXX_*_PTS_LAMB93_IGN69.copc.laz ]]; then
        echo "$input"
        return
    fi
    if [[ "$input" == LHD_FXX_*_PTS_LAMB93_IGN69 ]]; then
        echo "${input}.copc.laz"
        return
    fi
    # Bare coordinates like "1049_6895"
    echo "LHD_FXX_${input}_PTS_LAMB93_IGN69.copc.laz"
}

# List all available zone releases
list_zones() {
    log_info "Récupération de la liste des zones..."
    local page=1
    local total_pages=""

    while true; do
        local content
        content=$(curl -s "${API_URL}?page=${page}&limit=50") || true

        if [ -z "$content" ]; then
            break
        fi

        # Parse zone codes and dates
        echo "$content" | python3 -c "
import sys, xml.etree.ElementTree as ET
ns = {'atom': 'http://www.w3.org/2005/Atom'}
try:
    tree = ET.parse(sys.stdin)
    root = tree.getroot()
    for entry in root.findall('atom:entry', ns):
        title = entry.find('atom:title', ns)
        if title is not None and title.text:
            # Extract zone code and date
            parts = title.text.split('_')
            # NUALHD_1-0__LAZ_LAMB93_{ZONE}_{DATE}
            zone = parts[-2] if len(parts) >= 2 else '?'
            date = parts[-1] if len(parts) >= 1 else '?'
            print(f'{zone}\t{date}\t{title.text}')
except Exception:
    pass
" 2>/dev/null || true

        # Check if more pages
        if [ -z "$total_pages" ]; then
            total_pages=$(echo "$content" | python3 -c "
import sys, xml.etree.ElementTree as ET
ns = {'atom': 'http://www.w3.org/2005/Atom', 'gpf_dl': 'https://data.geopf.fr/annexes/ressources/xsd/gpf_dl.xsd'}
try:
    tree = ET.parse(sys.stdin)
    root = tree.getroot()
    pc = root.get('{https://data.geopf.fr/annexes/ressources/xsd/gpf_dl.xsd}pagecount', '1')
    print(pc)
except:
    print('1')
" 2>/dev/null)
        fi

        if [ "$page" -ge "${total_pages:-1}" ]; then
            break
        fi
        page=$((page + 1))
    done | sort
}

# Search for a tile across all zones
search_tile() {
    local tile_name="$1"
    local filename
    filename=$(normalize_name "$tile_name")

    log_info "Recherche de ${filename} dans toutes les zones..."

    local page=1
    local found=0
    local total_pages=""

    while true; do
        local content
        content=$(curl -s "${API_URL}?page=${page}&limit=50") || true
        [ -z "$content" ] && break

        # Get sub-resources and search for the file
        echo "$content" | python3 -c "
import sys, xml.etree.ElementTree as ET
ns = {'atom': 'http://www.w3.org/2005/Atom'}
try:
    tree = ET.parse(sys.stdin)
    root = tree.getroot()
    for entry in root.findall('atom:entry', ns):
        title = entry.find('atom:title', ns)
        if title is not None and title.text:
            print(title.text)
except:
    pass
" 2>/dev/null | while read -r release; do
            # Check if file exists in this release
            local url="${BASE_URL}/${release}/${filename}"
            local code
            code=$(curl -sI -L -o /dev/null -w "%{http_code}" "$url" 2>/dev/null)
            if [ "$code" = "200" ]; then
                log_ok "Trouvé: ${filename} dans la zone ${release}"
                echo "  URL: ${url}"
                found=1
            fi
        done

        if [ -z "$total_pages" ]; then
            total_pages=$(echo "$content" | python3 -c "
import sys, xml.etree.ElementTree as ET
ns = {'atom': 'http://www.w3.org/2005/Atom', 'gpf_dl': 'https://data.geopf.fr/annexes/ressources/xsd/gpf_dl.xsd'}
try:
    tree = ET.parse(sys.stdin)
    root = tree.getroot()
    pc = root.get('{https://data.geopf.fr/annexes/ressources/xsd/gpf_dl.xsd}pagecount', '1')
    print(pc)
except:
    print('1')
" 2>/dev/null)
        fi

        if [ "$page" -ge "${total_pages:-1}" ]; then
            break
        fi
        page=$((page + 1))
    done

    if [ "$found" -eq 0 ]; then
        log_err "${filename} non trouvé dans aucune zone"
    fi
}

# Download a single file with resume support
download_file() {
    local url="$1"
    local output_path="$2"
    local filename
    filename=$(basename "$output_path")

    # Resume download with retries
    local max_retries=15
    local retry=0

    while [ $retry -lt $max_retries ]; do
        retry=$((retry + 1))
        local result
        result=$(curl -L --http1.1 -C - -o "$output_path" "$url" 2>&1)
        local exit_code=$?

        if [ $exit_code -eq 0 ]; then
            # Verify it's a valid LAS/LAZ file
            local magic
            magic=$(head -c 4 "$output_path" 2>/dev/null | xxd -p 2>/dev/null || echo "")
            if [ "$magic" = "4c415346" ]; then
                local size
                size=$(stat -c%s "$output_path" 2>/dev/null || echo "0")
                log_ok "${filename} téléchargé (${size} octets)"
                return 0
            else
                log_err "${filename} n'est pas un fichier LAZ valide (magic: ${magic})"
                rm -f "$output_path"
                return 1
            fi
        fi

        # curl exit code 18 = partial download, resume
        if [ $exit_code -eq 18 ]; then
            local size
            size=$(stat -c%s "$output_path" 2>/dev/null || echo "0")
            log_warn "Téléchargement partiel (${size} octets), tentative ${retry}/${max_retries}..."
            sleep 2
            continue
        fi

        # HTTP 404
        if echo "$result" | grep -q "404"; then
            log_err "Fichier non trouvé (404): ${url}"
            rm -f "$output_path"
            return 1
        fi

        log_err "Erreur curl (${exit_code}): ${result}"
        return 1
    done

    # If we exhausted retries, check if partial file is usable
    local magic
    magic=$(head -c 4 "$output_path" 2>/dev/null | xxd -p 2>/dev/null || echo "")
    if [ "$magic" = "4c415346" ]; then
        local size
        size=$(stat -c%s "$output_path" 2>/dev/null || echo "0")
        log_warn "Fichier partiel mais valide: ${filename} (${size} octets)"
        return 0
    fi

    log_err "Échec après ${max_retries} tentatives"
    rm -f "$output_path"
    return 1
}

# Find which zone contains a given tile and download it
find_and_download() {
    local tile_name="$1"
    local output_dir="$2"
    local filename
    filename=$(normalize_name "$tile_name")
    local output_path="${output_dir}/${filename}"

    # If file already exists and is valid, skip
    if [ -f "$output_path" ]; then
        local magic
        magic=$(head -c 4 "$output_path" 2>/dev/null | xxd -p 2>/dev/null || echo "")
        if [ "$magic" = "4c415346" ]; then
            local size
            size=$(stat -c%s "$output_path" 2>/dev/null || echo "0")
            if [ "$size" -gt 1000000 ]; then
                log_info "${filename} déjà présent (${size} octets) — ignoré"
                return 0
            fi
        fi
        # File exists but seems invalid/truncated, re-download
        log_warn "${filename} existe mais semble incomplet, re-téléchargement..."
    fi

    log_info "Recherche de ${filename}..."

    # Try all zone releases
    local page=1
    local total_pages=""

    while true; do
        local content
        content=$(curl -s "${API_URL}?page=${page}&limit=50") || true
        [ -z "$content" ] && break

        echo "$content" | python3 -c "
import sys, xml.etree.ElementTree as ET
ns = {'atom': 'http://www.w3.org/2005/Atom'}
try:
    tree = ET.parse(sys.stdin)
    root = tree.getroot()
    for entry in root.findall('atom:entry', ns):
        title = entry.find('atom:title', ns)
        if title is not None and title.text:
            print(title.text)
except:
    pass
" 2>/dev/null | while read -r release; do
            local url="${BASE_URL}/${release}/${filename}"
            local code
            code=$(curl -sI -L -o /dev/null -w "%{http_code}" "$url" 2>/dev/null || echo "000")
            if [ "$code" = "200" ]; then
                log_ok "Trouvé dans la zone ${release}"
                download_file "$url" "$output_path"
                return 0
            fi
        done

        if [ -z "$total_pages" ]; then
            total_pages=$(echo "$content" | python3 -c "
import sys, xml.etree.ElementTree as ET
ns = {'atom': 'http://www.w3.org/2005/Atom', 'gpf_dl': 'https://data.geopf.fr/annexes/ressources/xsd/gpf_dl.xsd'}
try:
    tree = ET.parse(sys.stdin)
    root = tree.getroot()
    pc = root.get('{https://data.geopf.fr/annexes/ressources/xsd/gpf_dl.xsd}pagecount', '1')
    print(pc)
except:
    print('1')
" 2>/dev/null)
        fi

        if [ "$page" -ge "${total_pages:-1}" ]; then
            break
        fi
        page=$((page + 1))
    done

    log_err "${filename} non trouvé dans aucune zone disponible"
    return 1
}

# Download all tiles from a specific zone
download_zone() {
    local zone="$1"
    local output_dir="$2"
    local dry_run="${3:-false}"

    # Find the release name for this zone
    local release=""
    local page=1

    while true; do
        local content
        content=$(curl -s "${API_URL}?page=${page}&limit=50") || true
        [ -z "$content" ] && break

        release=$(echo "$content" | python3 -c "
import sys, xml.etree.ElementTree as ET
ns = {'atom': 'http://www.w3.org/2005/Atom'}
try:
    tree = ET.parse(sys.stdin)
    root = tree.getroot()
    for entry in root.findall('atom:entry', ns):
        title = entry.find('atom:title', ns)
        if title is not None and title.text:
            # Extract zone code from title like NUALHD_1-0__LAZ_LAMB93_RE_2025-02-17
            parts = title.text.split('_')
            z = parts[-2] if len(parts) >= 2 else ''
            if z == '${zone}':
                print(title.text)
                break
except:
    pass
" 2>/dev/null)

        if [ -n "$release" ]; then
            break
        fi
        page=$((page + 1))
        # Safety limit
        if [ $page -gt 25 ]; then
            break
        fi
    done

    if [ -z "$release" ]; then
        log_err "Zone '${zone}' non trouvée"
        return 1
    fi

    log_info "Zone ${zone}: ${release}"

    # Get list of files in this release
    local sub_url="${API_URL}/${release}?limit=50"
    local total_files=0
    local page=1

    while true; do
        local content
        content=$(curl -s "${API_URL}/${release}?page=${page}&limit=50") || true
        [ -z "$content" ] && break

        local files
        files=$(echo "$content" | python3 -c "
import sys, xml.etree.ElementTree as ET
ns = {'atom': 'http://www.w3.org/2005/Atom'}
try:
    tree = ET.parse(sys.stdin)
    root = tree.getroot()
    for entry in root.findall('atom:entry', ns):
        title = entry.find('atom:title', ns)
        if title is not None and title.text:
            print(title.text)
except:
    pass
" 2>/dev/null)

        if [ -z "$files" ]; then
            break
        fi

        local count
        count=$(echo "$files" | wc -l)
        total_files=$((total_files + count))

        if [ "$dry_run" = "true" ]; then
            echo "$files" | head -10
            echo "... (${count} fichiers sur cette page)"
        else
            echo "$files" | while read -r fname; do
                local url="${BASE_URL}/${release}/${fname}"
                download_file "$url" "${output_dir}/${fname}"
            done
        fi

        page=$((page + 1))
        # Safety limit
        if [ $page -gt 500 ]; then
            break
        fi
    done

    log_info "Total: ${total_files} fichiers dans la zone ${zone}"
}

# Show usage
usage() {
    cat <<'EOF'
download_lidar.sh — Téléchargement de fichiers LiDAR HD depuis l'IGN

Usage:
  ./download_lidar.sh <tuile> [tuile2...]    Télécharger une ou plusieurs tuiles
  ./download_lidar.sh --search <motif>        Chercher une tuile dans toutes les zones
  ./download_lidar.sh --list-zones            Lister les zones disponibles
  ./download_lidar.sh --zone <ZONE> [--dry-run]  Télécharger une zone entière
  ./download_lidar.sh --check [dossier/]      Vérifier l'intégrité des fichiers LAZ

Formats de tuile acceptés:
  1049_6895                                    Coordonnées seules
  LHD_FXX_1049_6895_PTS_LAMB93_IGN69          Nom complet sans extension
  LHD_FXX_1049_6895_PTS_LAMB93_IGN69.copc.laz Nom complet avec extension

Options:
  -o, --output DIR    Répertoire de destination (défaut: .)
  -n, --dry-run       Afficher sans télécharger (avec --zone)
  --check [DIR]       Vérifier l'intégrité des fichiers LAZ (défaut: ./)
  --list-zones        Lister toutes les zones disponibles
  --search MOTIF      Chercher un motif dans les noms de tuile
  --zone ZONE         Télécharger tous les fichiers d'une zone
  -h, --help          Afficher cette aide

Exemples:
  ./download_lidar.sh 1049_6895
  ./download_lidar.sh LHD_FXX_0713_6347_PTS_LAMB93_IGN69.copc.laz -o input/
  ./download_lidar.sh --search 1049
  ./download_lidar.sh --list-zones
  ./download_lidar.sh --zone RE -o input/
  ./download_lidar.sh --check input/
EOF
}

# Check integrity of LAZ files
check_files() {
    local dir="${1:-.}"
    local ok=0
    local fail=0

    log_info "Vérification de l'intégrité des fichiers LAZ dans ${dir}/"

    for f in "${dir}"/*.copc.laz "${dir}"/*.laz; do
        [ -f "$f" ] || continue
        local magic
        magic=$(head -c 4 "$f" 2>/dev/null | xxd -p 2>/dev/null || echo "")
        local size
        size=$(stat -c%s "$f" 2>/dev/null || echo "0")

        if [ "$magic" = "4c415346" ] && [ "$size" -gt 1000000 ]; then
            log_ok "$(basename $f) (${size} octets)"
            ok=$((ok + 1))
        elif [ "$magic" = "7b227469" ]; then
            log_err "$(basename $f) est une page HTML (404), pas un fichier LAZ"
            fail=$((fail + 1))
        elif [ "$size" -lt 1000 ]; then
            log_err "$(basename $f) trop petit (${size} octets) — probablement corrompu"
            fail=$((fail + 1))
        else
            log_warn "$(basename $f) magic=${magic}, taille=${size} — vérification nécessaire"
            fail=$((fail + 1))
        fi
    done

    log_info "Résultat: ${ok} OK, ${fail} problème(s)"
    return 0
}

# Main
CMD=""
TILES=()
ZONE=""
DRY_RUN=false

while [ $# -gt 0 ]; do
    case "$1" in
        -h|--help)
            usage
            exit 0
            ;;
        --list-zones)
            CMD="list-zones"
            shift
            ;;
        --search)
            CMD="search"
            shift
            TILES+=("$1")
            shift
            ;;
        --zone)
            CMD="zone"
            shift
            ZONE="$1"
            shift
            ;;
        --check)
            CMD="check"
            shift
            OUTPUT_DIR="${1:-.}"
            [ -d "$OUTPUT_DIR" ] && shift || true
            ;;
        -o|--output)
            shift
            OUTPUT_DIR="$1"
            shift
            ;;
        -n|--dry-run)
            DRY_RUN=true
            shift
            ;;
        -*)
            log_err "Option inconnue: $1"
            usage
            exit 1
            ;;
        *)
            TILES+=("$1")
            shift
            ;;
    esac
done

case "${CMD}" in
    list-zones)
        list_zones
        ;;
    search)
        for tile in "${TILES[@]}"; do
            search_tile "$tile"
        done
        ;;
    zone)
        if [ -z "$ZONE" ]; then
            log_err "Zone non spécifiée. Utilisez --zone <CODE>"
            exit 1
        fi
        mkdir -p "$OUTPUT_DIR"
        download_zone "$ZONE" "$OUTPUT_DIR" "$DRY_RUN"
        ;;
    check)
        check_files "$OUTPUT_DIR"
        ;;
    *)
        # Default: download tiles
        if [ ${#TILES[@]} -eq 0 ]; then
            usage
            exit 1
        fi
        mkdir -p "$OUTPUT_DIR"
        for tile in "${TILES[@]}"; do
            find_and_download "$tile" "$OUTPUT_DIR"
        done
        ;;
esac