mod v1_12;
mod v1_13;
mod v1_14;
mod v1_15;
use heed::RwTxn;
use v1_12::{V1_12_3_To_V1_13_0, V1_12_To_V1_12_3};
use v1_13::{V1_13_0_To_V1_13_1, V1_13_1_To_Latest_V1_13};
use v1_14::Latest_V1_13_To_Latest_V1_14;
use v1_15::Latest_V1_14_To_Latest_V1_15;

use crate::constants::{VERSION_MAJOR, VERSION_MINOR, VERSION_PATCH};
use crate::progress::{Progress, VariableNameStep};
use crate::{Index, InternalError, Result};

trait UpgradeIndex {
    /// Returns `true` if the index scheduler must regenerate its cached stats.
    fn upgrade(
        &self,
        wtxn: &mut RwTxn,
        index: &Index,
        original: (u32, u32, u32),
        progress: Progress,
    ) -> Result<bool>;
    fn target_version(&self) -> (u32, u32, u32);
}

/// Return true if the cached stats of the index must be regenerated
pub fn upgrade<MSP>(
    wtxn: &mut RwTxn,
    index: &Index,
    db_version: (u32, u32, u32),
    must_stop_processing: MSP,
    progress: Progress,
) -> Result<bool>
where
    MSP: Fn() -> bool + Sync,
{
    let from = index.get_version(wtxn)?.unwrap_or(db_version);
    let upgrade_functions: &[&dyn UpgradeIndex] = &[
        &V1_12_To_V1_12_3 {},
        &V1_12_3_To_V1_13_0 {},
        &V1_13_0_To_V1_13_1 {},
        &V1_13_1_To_Latest_V1_13 {},
        &Latest_V1_13_To_Latest_V1_14 {},
        &Latest_V1_14_To_Latest_V1_15 {},
        // This is the last upgrade function, it will be called when the index is up to date.
        // any other upgrade function should be added before this one.
        &ToCurrentNoOp {},
    ];

    let start = match from {
        (1, 12, 0..=2) => 0,
        (1, 12, 3..) => 1,
        (1, 13, 0) => 2,
        (1, 13, _) => 4,
        (1, 14, _) => 5,
        // We must handle the current version in the match because in case of a failure some index may have been upgraded but not other.
        (1, 15, _) => 6,
        (major, minor, patch) => {
            return Err(InternalError::CannotUpgradeToVersion(major, minor, patch).into())
        }
    };

    enum UpgradeVersion {}
    let upgrade_path = &upgrade_functions[start..];

    let mut current_version = from;
    let mut regenerate_stats = false;
    for (i, upgrade) in upgrade_path.iter().enumerate() {
        if (must_stop_processing)() {
            return Err(crate::Error::InternalError(InternalError::AbortedIndexation));
        }
        let target = upgrade.target_version();
        progress.update_progress(VariableNameStep::<UpgradeVersion>::new(
            format!(
                "Upgrading from v{}.{}.{} to v{}.{}.{}",
                current_version.0,
                current_version.1,
                current_version.2,
                target.0,
                target.1,
                target.2
            ),
            i as u32,
            upgrade_path.len() as u32,
        ));
        regenerate_stats |= upgrade.upgrade(wtxn, index, from, progress.clone())?;
        index.put_version(wtxn, target)?;
        current_version = target;
    }

    Ok(regenerate_stats)
}

#[allow(non_camel_case_types)]
struct ToCurrentNoOp {}

impl UpgradeIndex for ToCurrentNoOp {
    fn upgrade(
        &self,
        _wtxn: &mut RwTxn,
        _index: &Index,
        _original: (u32, u32, u32),
        _progress: Progress,
    ) -> Result<bool> {
        Ok(false)
    }

    fn target_version(&self) -> (u32, u32, u32) {
        (VERSION_MAJOR, VERSION_MINOR, VERSION_PATCH)
    }
}