use anyhow::Context;
use axum::http::HeaderMap;
use serde::Serialize;
use sha2::{Digest, Sha256};
use sqlx::{PgPool, Row};

use crate::credential_crypto::CredentialCrypto;

#[derive(Debug, Clone, Serialize)]
pub struct CameraPrincipal {
    pub principal_type: String,
    pub principal_id: String,
}

#[derive(Debug, Serialize)]
pub struct CameraAccessEntry {
    pub id: String,
    pub principal_type: String,
    pub principal_id: String,
    pub permission: String,
    pub created_at: String,
    pub expires_at: Option<String>,
}

#[derive(Debug, Clone, Serialize)]
pub struct StoredCameraCredential {
    pub camera_id: String,
    pub username: Option<String>,
    pub password: Option<String>,
    pub bearer_token: Option<String>,
    pub headers: serde_json::Value,
    pub encryption_key_id: Option<String>,
    pub rotation_count: i32,
}

pub async fn resolve_principal(
    headers: &HeaderMap,
    pool: Option<&PgPool>,
) -> anyhow::Result<Option<CameraPrincipal>> {
    if let Some(user_id) = headers.get("x-user-id").and_then(|value| value.to_str().ok()) {
        let trimmed = user_id.trim();
        if !trimmed.is_empty() {
            return Ok(Some(CameraPrincipal {
                principal_type: "user".to_string(),
                principal_id: trimmed.to_string(),
            }));
        }
    }

    let api_key = match headers.get("x-api-key").and_then(|value| value.to_str().ok()) {
        Some(value) if !value.trim().is_empty() => value.trim(),
        _ => return Ok(None),
    };

    let Some(pool) = pool else {
        return Ok(None);
    };
    let prefix: String = api_key.chars().take(8).collect();
    let hash = format!("{:x}", Sha256::digest(api_key.as_bytes()));
    let row = sqlx::query(
        r#"
        SELECT id
        FROM api_keys
        WHERE key_prefix = $1
          AND key_hash = $2
          AND revoked_at IS NULL
          AND (expires_at IS NULL OR expires_at > NOW())
        LIMIT 1
        "#,
    )
    .bind(prefix)
    .bind(hash)
    .fetch_optional(pool)
    .await
    .context("Neizdevās validēt x-api-key")?;

    Ok(row.map(|row| CameraPrincipal {
        principal_type: "api_key".to_string(),
        principal_id: row.get::<uuid::Uuid, _>("id").to_string(),
    }))
}

pub async fn ensure_access(
    pool: Option<&PgPool>,
    camera_id: &str,
    principal: Option<&CameraPrincipal>,
    permission: &str,
    auth_required: bool,
) -> anyhow::Result<bool> {
    let Some(pool) = pool else {
        return Ok(!auth_required || principal.is_some());
    };

    let count: i64 = sqlx::query_scalar(
        "SELECT COUNT(*) FROM vision_camera_access WHERE camera_id = $1",
    )
    .bind(camera_id)
    .fetch_one(pool)
    .await
    .context("Neizdevās nolasīt camera access count")?;

    if count == 0 {
        return Ok(!auth_required || principal.is_some());
    }

    let Some(principal) = principal else {
        return Ok(false);
    };

    let row = sqlx::query(
        r#"
        SELECT 1
        FROM vision_camera_access
        WHERE camera_id = $1
          AND principal_type = $2
          AND principal_id = $3
          AND permission = $4
          AND (expires_at IS NULL OR expires_at > NOW())
        LIMIT 1
        "#,
    )
    .bind(camera_id)
    .bind(&principal.principal_type)
    .bind(&principal.principal_id)
    .bind(permission)
    .fetch_optional(pool)
    .await
    .context("Neizdevās pārbaudīt camera access")?;

    Ok(row.is_some())
}

pub async fn grant_access(
    pool: &PgPool,
    camera_id: &str,
    principal_type: &str,
    principal_id: &str,
    permission: &str,
) -> anyhow::Result<()> {
    sqlx::query(
        r#"
        INSERT INTO vision_camera_access (camera_id, principal_type, principal_id, permission)
        VALUES ($1, $2, $3, $4)
        ON CONFLICT (camera_id, principal_type, principal_id, permission) DO NOTHING
        "#,
    )
    .bind(camera_id)
    .bind(principal_type)
    .bind(principal_id)
    .bind(permission)
    .execute(pool)
    .await
    .context("Neizdevās piešķirt camera access")?;
    Ok(())
}

pub async fn list_access(pool: &PgPool, camera_id: &str) -> anyhow::Result<Vec<CameraAccessEntry>> {
    let rows = sqlx::query(
        r#"
        SELECT id, principal_type, principal_id, permission, created_at, expires_at
        FROM vision_camera_access
        WHERE camera_id = $1
        ORDER BY created_at DESC
        "#,
    )
    .bind(camera_id)
    .fetch_all(pool)
    .await
    .context("Neizdevās nolasīt camera access sarakstu")?;

    Ok(rows
        .into_iter()
        .map(|row| CameraAccessEntry {
            id: row.get::<uuid::Uuid, _>("id").to_string(),
            principal_type: row.get("principal_type"),
            principal_id: row.get("principal_id"),
            permission: row.get("permission"),
            created_at: row
                .get::<chrono::DateTime<chrono::Utc>, _>("created_at")
                .to_rfc3339(),
            expires_at: row
                .get::<Option<chrono::DateTime<chrono::Utc>>, _>("expires_at")
                .map(|value| value.to_rfc3339()),
        })
        .collect())
}

pub async fn revoke_access(pool: &PgPool, access_id: &str) -> anyhow::Result<()> {
    let access_id = uuid::Uuid::parse_str(access_id).context("Nederīgs access_id")?;
    sqlx::query("DELETE FROM vision_camera_access WHERE id = $1")
        .bind(access_id)
        .execute(pool)
        .await
        .context("Neizdevās noņemt camera access")?;
    Ok(())
}

pub async fn upsert_credentials(
    pool: &PgPool,
    crypto: &CredentialCrypto,
    camera_id: &str,
    username: Option<&str>,
    password: Option<&str>,
    bearer_token: Option<&str>,
    headers: &serde_json::Value,
    actor: Option<&CameraPrincipal>,
) -> anyhow::Result<()> {
    let encrypted_password = match password {
        Some(value) if !value.is_empty() => Some(crypto.encrypt(value)?.0),
        _ => None,
    };
    let (encrypted_bearer, key_id) = match bearer_token {
        Some(value) if !value.is_empty() => {
            let (cipher, key) = crypto.encrypt(value)?;
            (Some(cipher), Some(key.key_id))
        }
        _ => (None, Some(crypto.current_key_id()?)),
    };
    sqlx::query(
        r#"
        INSERT INTO vision_camera_credentials (
            camera_id, username, password_encrypted, bearer_token_encrypted, headers_json, encryption_key_id
        )
        VALUES ($1, $2, $3, $4, $5, $6)
        ON CONFLICT (camera_id) DO UPDATE SET
            username = EXCLUDED.username,
            password_encrypted = EXCLUDED.password_encrypted,
            bearer_token_encrypted = EXCLUDED.bearer_token_encrypted,
            headers_json = EXCLUDED.headers_json,
            encryption_key_id = EXCLUDED.encryption_key_id
        "#,
    )
    .bind(camera_id)
    .bind(username)
    .bind(encrypted_password)
    .bind(encrypted_bearer)
    .bind(headers)
    .bind(key_id)
    .execute(pool)
    .await
    .context("Neizdevās saglabāt camera credentials")?;
    write_credential_audit(pool, camera_id, "stored", actor, headers, crypto.current_key_id().ok().as_deref())
        .await?;
    Ok(())
}

pub async fn load_credentials(
    pool: &PgPool,
    crypto: &CredentialCrypto,
    camera_id: &str,
    actor: Option<&CameraPrincipal>,
) -> anyhow::Result<Option<StoredCameraCredential>> {
    let row = sqlx::query(
        r#"
        SELECT camera_id, username, password_encrypted, bearer_token_encrypted, headers_json, encryption_key_id, rotation_count
        FROM vision_camera_credentials
        WHERE camera_id = $1
        LIMIT 1
        "#,
    )
    .bind(camera_id)
    .fetch_optional(pool)
    .await
    .context("Neizdevās nolasīt camera credentials")?;

    let result = row
        .map(|row| -> anyhow::Result<StoredCameraCredential> {
            let password = row
                .get::<Option<String>, _>("password_encrypted")
                .map(|value| crypto.decrypt(&value))
                .transpose()?;
            let bearer_token = row
                .get::<Option<String>, _>("bearer_token_encrypted")
                .map(|value| crypto.decrypt(&value))
                .transpose()?;
            Ok(StoredCameraCredential {
                camera_id: row.get("camera_id"),
                username: row.get("username"),
                password,
                bearer_token,
                headers: row.get("headers_json"),
                encryption_key_id: row.get("encryption_key_id"),
                rotation_count: row.get("rotation_count"),
            })
        })
        .transpose()?;
    if result.is_some() {
        write_credential_audit(pool, camera_id, "read", actor, &serde_json::json!({}), None).await?;
    }
    Ok(result)
}

pub async fn rotate_credentials(
    pool: &PgPool,
    crypto: &CredentialCrypto,
    actor: Option<&CameraPrincipal>,
) -> anyhow::Result<u64> {
    let rows = sqlx::query(
        r#"
        SELECT camera_id, username, password_encrypted, bearer_token_encrypted, headers_json
        FROM vision_camera_credentials
        "#,
    )
    .fetch_all(pool)
    .await
    .context("Neizdevās nolasīt credentials rotācijai")?;
    let mut rotated = 0_u64;
    for row in rows {
        let camera_id: String = row.get("camera_id");
        let username: Option<String> = row.get("username");
        let password = row
            .get::<Option<String>, _>("password_encrypted")
            .map(|value| crypto.decrypt(&value))
            .transpose()?;
        let bearer_token = row
            .get::<Option<String>, _>("bearer_token_encrypted")
            .map(|value| crypto.decrypt(&value))
            .transpose()?;
        let headers: serde_json::Value = row.get("headers_json");
        let encrypted_password = match password.as_deref() {
            Some(value) => Some(crypto.encrypt(value)?.0),
            None => None,
        };
        let encrypted_bearer = match bearer_token.as_deref() {
            Some(value) => Some(crypto.encrypt(value)?.0),
            None => None,
        };
        sqlx::query(
            r#"
            UPDATE vision_camera_credentials
            SET username = $2,
                password_encrypted = $3,
                bearer_token_encrypted = $4,
                headers_json = $5,
                encryption_key_id = $6,
                rotation_count = rotation_count + 1
            WHERE camera_id = $1
            "#,
        )
        .bind(&camera_id)
        .bind(username)
        .bind(encrypted_password)
        .bind(encrypted_bearer)
        .bind(headers)
        .bind(crypto.current_key_id()?)
        .execute(pool)
        .await
        .context("Neizdevās pāršifrēt camera credential")?;
        write_credential_audit(
            pool,
            &camera_id,
            "rotated",
            actor,
            &serde_json::json!({ "rotation_count_increment": 1 }),
            crypto.current_key_id().ok().as_deref(),
        )
        .await?;
        rotated += 1;
    }
    Ok(rotated)
}

async fn write_credential_audit(
    pool: &PgPool,
    camera_id: &str,
    action: &str,
    actor: Option<&CameraPrincipal>,
    metadata: &serde_json::Value,
    encryption_key_id: Option<&str>,
) -> anyhow::Result<()> {
    sqlx::query(
        r#"
        INSERT INTO vision_camera_credential_audit (
            camera_id, action, actor_principal_type, actor_principal_id, encryption_key_id, metadata_json
        )
        VALUES ($1, $2, $3, $4, $5, $6)
        "#,
    )
    .bind(camera_id)
    .bind(action)
    .bind(actor.map(|item| item.principal_type.as_str()))
    .bind(actor.map(|item| item.principal_id.as_str()))
    .bind(encryption_key_id)
    .bind(metadata)
    .execute(pool)
    .await
    .context("Neizdevās saglabāt credential audit")?;
    Ok(())
}