use anyhow::Context;
use assert_cmd::cargo_bin_cmd;
use std::cmp::Ordering;
use std::fs::read_dir;
use std::ops::Index;
use std::path::{Path, PathBuf};
use tempfile::TempDir;

#[derive(Debug, PartialEq, Eq)]
struct FileName {
    id: u64,
    description: String,
    suffix: String,
}

impl PartialOrd<Self> for FileName {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        if self.id != other.id {
            self.id.partial_cmp(&other.id)
        } else {
            self.suffix.partial_cmp(&other.suffix)
        }
    }
}

impl FileName {
    fn assert_is_timestamp(&self) {
        assert!(
            self.id > 20200101000000,
            "{self:?} is too low for a timestamp"
        );
    }
}

impl From<PathBuf> for FileName {
    fn from(path: PathBuf) -> Self {
        let filename = path.file_name().unwrap().to_string_lossy();
        let (id, rest) = filename.split_once("_").unwrap();
        let id: u64 = id.parse().unwrap();
        let (description, suffix) = rest.split_once(".").unwrap();
        Self {
            id,
            description: description.to_string(),
            suffix: suffix.to_string(),
        }
    }
}

struct AddMigrationsResult(Vec<FileName>);
impl AddMigrationsResult {
    fn len(&self) -> usize {
        self.0.len()
    }
    fn assert_is_reversible(&self) {
        let mut up_cnt = 0;
        let mut down_cnt = 0;
        for file in self.0.iter() {
            if file.suffix == "down.sql" {
                down_cnt += 1;
            } else if file.suffix == "up.sql" {
                up_cnt += 1;
            } else {
                panic!("unknown suffix for {file:?}");
            }
            assert!(file.description.starts_with("hello_world"));
        }
        assert_eq!(up_cnt, down_cnt);
    }
    fn assert_is_not_reversible(&self) {
        for file in self.0.iter() {
            assert_eq!(file.suffix, "sql");
            assert!(file.description.starts_with("hello_world"));
        }
    }
}

impl Index<usize> for AddMigrationsResult {
    type Output = FileName;

    fn index(&self, index: usize) -> &Self::Output {
        &self.0[index]
    }
}

struct AddMigrations {
    tempdir: TempDir,
    config_arg: Option<String>,
}

impl AddMigrations {
    fn new() -> anyhow::Result<Self> {
        anyhow::Ok(Self {
            tempdir: TempDir::new()?,
            config_arg: None,
        })
    }

    fn with_config(mut self, filename: &str) -> anyhow::Result<Self> {
        let path = format!("./tests/assets/{filename}");

        let path = std::fs::canonicalize(&path)
            .with_context(|| format!("error canonicalizing path {path:?}"))?;

        let path = path
            .to_str()
            .with_context(|| format!("canonicalized version of path {path:?} is not UTF-8"))?;

        self.config_arg = Some(format!("--config={path}"));
        Ok(self)
    }

    fn run(
        &self,
        description: &str,
        revesible: bool,
        timestamp: bool,
        sequential: bool,
        expect_success: bool,
    ) -> anyhow::Result<&'_ Self> {
        let cmd_result = cargo_bin_cmd!("cargo-sqlx")
            .current_dir(&self.tempdir)
            .args(
                [
                    vec!["sqlx", "migrate", "add", description],
                    self.config_arg.as_deref().map_or(vec![], |arg| vec![arg]),
                    match revesible {
                        true => vec!["-r"],
                        false => vec![],
                    },
                    match timestamp {
                        true => vec!["--timestamp"],
                        false => vec![],
                    },
                    match sequential {
                        true => vec!["--sequential"],
                        false => vec![],
                    },
                ]
                .concat(),
            )
            .env("RUST_BACKTRACE", "1")
            .assert();
        if expect_success {
            cmd_result.success();
        } else {
            cmd_result.failure();
        }
        anyhow::Ok(self)
    }
    fn fs_output(&self) -> anyhow::Result<AddMigrationsResult> {
        let files = recurse_files(&self.tempdir)?;
        let mut fs_paths = Vec::with_capacity(files.len());
        for path in files {
            let relative_path = path.strip_prefix(self.tempdir.path())?.to_path_buf();
            fs_paths.push(FileName::from(relative_path));
        }
        Ok(AddMigrationsResult(fs_paths))
    }
}

fn recurse_files(path: impl AsRef<Path>) -> anyhow::Result<Vec<PathBuf>> {
    let mut buf = vec![];
    let entries = read_dir(path)?;

    for entry in entries {
        let entry = entry?;
        let meta = entry.metadata()?;

        if meta.is_dir() {
            let mut subdir = recurse_files(entry.path())?;
            buf.append(&mut subdir);
        }

        if meta.is_file() {
            buf.push(entry.path());
        }
    }
    buf.sort();
    Ok(buf)
}

#[test]
fn add_migration_error_ambiguous() -> anyhow::Result<()> {
    for reversible in [true, false] {
        let files = AddMigrations::new()?
            // Passing both `--timestamp` and `--reversible` should result in an error.
            .run("hello world", reversible, true, true, false)?
            .fs_output()?;

        // Assert that no files are created
        assert_eq!(files.0, []);
    }
    Ok(())
}

#[test]
fn add_migration_sequential() -> anyhow::Result<()> {
    {
        let files = AddMigrations::new()?
            .run("hello world", false, false, true, true)?
            .fs_output()?;
        assert_eq!(files.len(), 1);
        files.assert_is_not_reversible();
        assert_eq!(files.0[0].id, 1);
    }
    {
        let files = AddMigrations::new()?
            .run("hello world1", false, false, true, true)?
            .run("hello world2", true, false, true, true)?
            .fs_output()?;
        assert_eq!(files.len(), 3);
        assert_eq!(files.0[0].id, 1);
        assert_eq!(files.0[1].id, 2);
        assert_eq!(files.0[1].suffix, "down.sql");
        assert_eq!(files.0[2].id, 2);
        assert_eq!(files.0[2].suffix, "up.sql");
    }
    Ok(())
}
#[test]
fn add_migration_sequential_reversible() -> anyhow::Result<()> {
    {
        let files = AddMigrations::new()?
            .run("hello world", true, false, true, true)?
            .fs_output()?;
        assert_eq!(files.len(), 2);
        files.assert_is_reversible();
        assert_eq!(files.0[0].id, 1);
        assert_eq!(files.0[0].id, 1);
    }
    {
        let files = AddMigrations::new()?
            .run("hello world1", true, false, true, true)?
            .run("hello world2", true, true, false, true)?
            .run("hello world3", true, false, true, true)?
            .fs_output()?;
        assert_eq!(files.len(), 6);
        files.assert_is_reversible();
        assert_eq!(files.0[0].id, 1);
        assert_eq!(files.0[1].id, 1);
        // sequential -> timestamp is one way
        files.0[2].assert_is_timestamp();
        files.0[3].assert_is_timestamp();
        files.0[4].assert_is_timestamp();
        files.0[5].assert_is_timestamp();
    }
    Ok(())
}

#[test]
fn add_migration_timestamp() -> anyhow::Result<()> {
    {
        let files = AddMigrations::new()?
            .run("hello world", false, true, false, true)?
            .fs_output()?;
        assert_eq!(files.len(), 1);
        files.assert_is_not_reversible();
        files.0[0].assert_is_timestamp();
    }
    {
        let files = AddMigrations::new()?
            .run("hello world1", false, true, false, true)?
            .run("hello world2", true, false, true, true)?
            .fs_output()?;
        assert_eq!(files.len(), 3);
        files.0[0].assert_is_timestamp();
        // sequential -> timestamp is one way
        files.0[1].assert_is_timestamp();
        files.0[2].assert_is_timestamp();
    }
    Ok(())
}

#[test]
fn add_migration_timestamp_reversible() -> anyhow::Result<()> {
    {
        let files = AddMigrations::new()?
            .run("hello world", true, false, false, true)?
            .fs_output()?;

        assert_eq!(files.len(), 2);
        files.assert_is_reversible();

        // .up.sql and .down.sql
        files[0].assert_is_timestamp();
        assert_eq!(files[1].id, files[0].id);
    }
    {
        let files = AddMigrations::new()?
            .run("hello world", true, true, false, true)?
            .fs_output()?;

        assert_eq!(files.len(), 2);
        files.assert_is_reversible();

        // .up.sql and .down.sql
        files[0].assert_is_timestamp();
        assert_eq!(files[1].id, files[0].id);
    }
    {
        let files = AddMigrations::new()?
            .run("hello world1", true, true, false, true)?
            // Reversible should be inferred, but sequential should be forced
            .run("hello world2", false, false, true, true)?
            .fs_output()?;

        assert_eq!(files.len(), 4);
        files.assert_is_reversible();

        // First pair: .up.sql and .down.sql
        files[0].assert_is_timestamp();
        assert_eq!(files[1].id, files[0].id);

        // Second pair; we set `--sequential` so this version should be one higher
        assert_eq!(files[2].id, files[1].id + 1);
        assert_eq!(files[3].id, files[1].id + 1);
    }
    Ok(())
}

#[test]
fn add_migration_config_default_type_reversible() -> anyhow::Result<()> {
    let files = AddMigrations::new()?
        .with_config("config_default_type_reversible.toml")?
        // Type should default to reversible without any flags
        .run("hello world", false, false, false, true)?
        .run("hello world2", false, false, false, true)?
        .run("hello world3", false, false, false, true)?
        .fs_output()?;

    assert_eq!(files.len(), 6);
    files.assert_is_reversible();

    files[0].assert_is_timestamp();
    assert_eq!(files[1].id, files[0].id);

    files[2].assert_is_timestamp();
    assert_eq!(files[3].id, files[2].id);

    files[4].assert_is_timestamp();
    assert_eq!(files[5].id, files[4].id);

    Ok(())
}

#[test]
fn add_migration_config_default_versioning_sequential() -> anyhow::Result<()> {
    let files = AddMigrations::new()?
        .with_config("config_default_versioning_sequential.toml")?
        // Versioning should default to timestamp without any flags
        .run("hello world", false, false, false, true)?
        .run("hello world2", false, false, false, true)?
        .run("hello world3", false, false, false, true)?
        .fs_output()?;

    assert_eq!(files.len(), 3);
    files.assert_is_not_reversible();

    assert_eq!(files[0].id, 1);
    assert_eq!(files[1].id, 2);
    assert_eq!(files[2].id, 3);

    Ok(())
}

#[test]
fn add_migration_config_default_versioning_timestamp() -> anyhow::Result<()> {
    let migrations = AddMigrations::new()?;

    migrations
        .run("hello world", false, false, true, true)?
        // Default config should infer sequential even without passing `--sequential`
        .run("hello world2", false, false, false, true)?
        .run("hello world3", false, false, false, true)?;

    let files = migrations.fs_output()?;

    assert_eq!(files.len(), 3);
    files.assert_is_not_reversible();

    assert_eq!(files[0].id, 1);
    assert_eq!(files[1].id, 2);
    assert_eq!(files[2].id, 3);

    // Now set a config that uses `default-versioning = "timestamp"`
    let migrations = migrations.with_config("config_default_versioning_timestamp.toml")?;

    // Now the default should be a timestamp
    migrations
        .run("hello world4", false, false, false, true)?
        .run("hello world5", false, false, false, true)?;

    let files = migrations.fs_output()?;

    assert_eq!(files.len(), 5);
    files.assert_is_not_reversible();

    assert_eq!(files[0].id, 1);
    assert_eq!(files[1].id, 2);
    assert_eq!(files[2].id, 3);

    files[3].assert_is_timestamp();
    files[4].assert_is_timestamp();

    Ok(())
}