#!/bin/bash

set -euo pipefail

if [ $# -eq 0 ]; then
    echo "Usage: $0 <export-file1.json> [export-file2.json] ..." >&2
    exit 1
fi

jq -n --slurpfile files <(
    for file in "$@"; do
        basename=$(basename "$file")
        date_prefix=$(echo "$basename" | grep -oE '^[0-9]{4}-[0-9]{2}-[0-9]{2}' || echo "0000-00-00")

        jq --arg file "$file" --arg date "$date_prefix" '. + {sourceFile: $file, fileDate: $date}' "$file"
    done | jq -s '.'
) '
# Sort files by date (later dates have priority for tie-breaking)
($files[0] | sort_by(.fileDate)) as $sorted_files |

# Merge playlists
($sorted_files | map(.playlists // {} | to_entries) | flatten | group_by(.key) | map({
    key: .[0].key,
    value: (
        # Get the playlist name
        .[0].key as $playlist_name |

        # Collect all videos from all versions with metadata
        (map(.value) | flatten | unique_by(.url)) as $all_videos |

        # For each video, find its earliest position
        $all_videos | map(. as $video |
            # Find earliest position across all files
            ([$sorted_files[] |
                select(.playlists[$playlist_name]) |
                .playlists[$playlist_name] |
                to_entries[] |
                select(.value.url == $video.url) |
                {index: .key, date: .}
            ] |
            if length > 0 then
                min_by(.date)
            else
                {index: 999999, date: {fileDate: "9999-99-99"}}
            end) as $earliest |

            # Get latest video data
            ([$sorted_files[] |
                select(.playlists[$playlist_name]) |
                .playlists[$playlist_name][] |
                select(.url == $video.url)
            ] | last) as $latest_video |

            $latest_video + {
                _sort_date: ($sorted_files | map(select(.playlists[$playlist_name] and (.playlists[$playlist_name] | map(.url) | contains([$video.url])))) | .[0].fileDate),
                _sort_index: $earliest.index
            }
        ) |
        # Sort by earliest appearance
        sort_by([._sort_date, ._sort_index]) |
        # Remove sort keys
        map(del(._sort_date, ._sort_index))
    )
}) | from_entries) as $merged_playlists |

# Merge playback history
($sorted_files | map(.playbackHistory // {} | to_entries) | flatten | group_by(.key) | map({
    key: .[0].key,
    value: (
        # For each video in history, merge all events and metadata
        map(.value) |
        {
            url: (map(.url) | last),
            title: (map(.title) | last),
            tags: (map(.tags // []) | flatten | unique),
            history: (map(.history // []) | flatten | unique_by(.timestamp) | sort_by(.timestamp))
        }
    )
}) | from_entries) as $merged_history |

# Collect all open tabs (unique by URL, keep latest title)
($sorted_files | map(.openTabs // []) | flatten | group_by(.url) | map(last)) as $merged_tabs |

# Output merged result
{
    playlists: $merged_playlists,
    playbackHistory: $merged_history,
    openTabs: $merged_tabs,
    exportDate: (now | todate),
    mergedFrom: ($sorted_files | map({file: .sourceFile, date: .fileDate}))
}
'