use axum::extract::{Path, State};
use axum::{Json, Router};
use uuid::Uuid;

use crate::app_state::AppState;
use crate::error_handlers::AppError;
use crate::models::{AghanimKind, Build, BuildConfig, Enchantment, EnchantmentStageResult, Item, NeutralStageResult};
use crate::roll;

pub async fn init_build_handlers(state: AppState) -> Router {
    Router::new()
        .route("/api/builds", axum::routing::post(post_builds))
        .route("/api/builds/{id}/reroll/hero", axum::routing::post(reroll_hero))
        .route("/api/builds/{id}/reroll/item-slot/{slot}", axum::routing::post(reroll_item_slot))
        .route("/api/builds/{id}/reroll/neutral/{tier}", axum::routing::post(reroll_neutral))
        .route("/api/builds/{id}/reroll/enchantment/{tier}", axum::routing::post(reroll_enchantment))
        .route("/api/builds/{id}/item-slot/{slot}", axum::routing::patch(patch_item_slot))
        .route("/api/builds/{id}/neutral/{tier}", axum::routing::patch(patch_neutral))
        .route("/api/builds/{id}/enchantment/{tier}", axum::routing::patch(patch_enchantment))
        .with_state(state)
}

fn get_build(state: &AppState, id: &str) -> Result<Build, AppError> {
    state.builds.lock().unwrap().get(id).cloned().ok_or(AppError::NotFound)
}

fn save_build(state: &AppState, build: Build) {
    state.builds.lock().unwrap().insert(build.id.clone(), build);
}

async fn post_builds(State(state): State<AppState>, Json(config): Json<BuildConfig>) -> Result<Json<Build>, AppError> {
    let hero = roll::roll_hero(&state.pool, &config).await?;
    let item_slots = roll::roll_item_slots(&state.pool, &config).await?;
    let neutral_items = roll::roll_neutral_stages(&state.pool, &config, state.neutral_tier_gate_chance).await?;
    let enchantments = roll::roll_enchantment_stages(&state.pool, &config, hero.primary_attribute).await?;
    let aghanim_scepter =
        roll::derive_aghanim_result(&item_slots, "Aghanim's Scepter", AghanimKind::Scepter, config.aghanim_scepter_timing);
    let aghanim_shard =
        roll::derive_aghanim_result(&item_slots, "Aghanim's Shard", AghanimKind::Shard, config.aghanim_shard_timing);

    let build = Build {
        id: Uuid::new_v4().to_string(),
        config,
        hero,
        item_slots,
        neutral_items,
        enchantments,
        aghanim_scepter,
        aghanim_shard,
    };

    save_build(&state, build.clone());
    Ok(Json(build))
}

async fn reroll_hero(State(state): State<AppState>, Path(id): Path<String>) -> Result<Json<Build>, AppError> {
    let mut build = get_build(&state, &id)?;
    build.hero = roll::roll_hero(&state.pool, &build.config).await?;
    // Rerolling the hero starts a fresh neutral/enchantment progression too --
    // enchantment eligibility depends on primary attribute, and neutral items
    // are reset alongside it as a deliberate "new hero, new itemization" reset.
    build.neutral_items = roll::roll_neutral_stages(&state.pool, &build.config, state.neutral_tier_gate_chance).await?;
    build.enchantments = roll::roll_enchantment_stages(&state.pool, &build.config, build.hero.primary_attribute).await?;
    save_build(&state, build.clone());
    Ok(Json(build))
}

async fn reroll_item_slot(
    State(state): State<AppState>,
    Path((id, slot)): Path<(String, i32)>,
) -> Result<Json<Build>, AppError> {
    let mut build = get_build(&state, &id)?;
    let updated_slot = roll::roll_one_item_slot(&state.pool, &build.config, &build.item_slots, slot).await?;
    if let Some(s) = build.item_slots.iter_mut().find(|s| s.slot == slot) {
        *s = updated_slot;
    }
    build.aghanim_scepter = roll::derive_aghanim_result(
        &build.item_slots,
        "Aghanim's Scepter",
        AghanimKind::Scepter,
        build.config.aghanim_scepter_timing,
    );
    build.aghanim_shard = roll::derive_aghanim_result(
        &build.item_slots,
        "Aghanim's Shard",
        AghanimKind::Shard,
        build.config.aghanim_shard_timing,
    );
    save_build(&state, build.clone());
    Ok(Json(build))
}

async fn reroll_neutral(
    State(state): State<AppState>,
    Path((id, tier)): Path<(String, i32)>,
) -> Result<Json<Build>, AppError> {
    let mut build = get_build(&state, &id)?;

    let stage = if build.config.disable_all_neutral_rolls || build.config.disable_neutral_artifact_randomness {
        // Randomness is off for this dimension entirely -- rerolling a single
        // tier shouldn't be able to bypass that and roll something anyway.
        NeutralStageResult { tier, attempts: vec![], resolved: None, requires_manual_pick: true, tier_gate_won: None }
    } else {
        let carry = build.neutral_items.iter().find(|s| s.tier == tier - 1).and_then(|s| s.resolved.clone());
        let gated = tier > 1 && !build.config.neutral_tier_reroll_enabled;
        roll::roll_neutral_stage(&state.pool, tier, carry, gated, state.neutral_tier_gate_chance).await?
    };

    if let Some(s) = build.neutral_items.iter_mut().find(|s| s.tier == tier) {
        *s = stage;
    }
    save_build(&state, build.clone());
    Ok(Json(build))
}

async fn reroll_enchantment(
    State(state): State<AppState>,
    Path((id, tier)): Path<(String, i32)>,
) -> Result<Json<Build>, AppError> {
    let mut build = get_build(&state, &id)?;

    let stage = if build.config.disable_all_neutral_rolls || build.config.disable_enchantment_randomness {
        EnchantmentStageResult { tier, resolved: None, requires_manual_pick: true }
    } else {
        roll::roll_enchantment_stage(&state.pool, tier, build.hero.primary_attribute).await?
    };

    if let Some(s) = build.enchantments.iter_mut().find(|s| s.tier == tier) {
        *s = stage;
    }
    save_build(&state, build.clone());
    Ok(Json(build))
}

#[derive(serde::Deserialize)]
#[serde(rename_all = "camelCase")]
struct ItemIdBody {
    item_id: i32,
}

#[derive(serde::Deserialize)]
#[serde(rename_all = "camelCase")]
struct EnchantmentIdBody {
    enchantment_id: i32,
}

async fn patch_item_slot(
    State(state): State<AppState>,
    Path((id, slot)): Path<(String, i32)>,
    Json(body): Json<ItemIdBody>,
) -> Result<Json<Build>, AppError> {
    let mut build = get_build(&state, &id)?;
    let item: Option<Item> =
        sqlx::query_as("SELECT id, name, source, min_tier, max_tier, min_grade, max_grade, image_url FROM items WHERE id = $1")
            .bind(body.item_id)
            .fetch_optional(&state.pool)
            .await?;
    let mut item = item.ok_or_else(|| AppError::BadRequest(format!("No item with id {}", body.item_id)))?;
    roll::hydrate_item_tags(&state.pool, &mut item).await?;

    if let Some(s) = build.item_slots.iter_mut().find(|s| s.slot == slot) {
        s.item = Some(item);
        s.is_manual = true;
    }
    build.aghanim_scepter = roll::derive_aghanim_result(
        &build.item_slots,
        "Aghanim's Scepter",
        AghanimKind::Scepter,
        build.config.aghanim_scepter_timing,
    );
    build.aghanim_shard = roll::derive_aghanim_result(
        &build.item_slots,
        "Aghanim's Shard",
        AghanimKind::Shard,
        build.config.aghanim_shard_timing,
    );
    save_build(&state, build.clone());
    Ok(Json(build))
}

async fn patch_neutral(
    State(state): State<AppState>,
    Path((id, tier)): Path<(String, i32)>,
    Json(body): Json<ItemIdBody>,
) -> Result<Json<Build>, AppError> {
    let mut build = get_build(&state, &id)?;
    let item: Option<Item> =
        sqlx::query_as("SELECT id, name, source, min_tier, max_tier, min_grade, max_grade, image_url FROM items WHERE id = $1")
            .bind(body.item_id)
            .fetch_optional(&state.pool)
            .await?;
    let mut item = item.ok_or_else(|| AppError::BadRequest(format!("No item with id {}", body.item_id)))?;
    roll::hydrate_item_tags(&state.pool, &mut item).await?;

    if let Some(s) = build.neutral_items.iter_mut().find(|s| s.tier == tier) {
        s.resolved = Some(item);
        s.requires_manual_pick = false;
    }
    save_build(&state, build.clone());
    Ok(Json(build))
}

async fn patch_enchantment(
    State(state): State<AppState>,
    Path((id, tier)): Path<(String, i32)>,
    Json(body): Json<EnchantmentIdBody>,
) -> Result<Json<Build>, AppError> {
    let mut build = get_build(&state, &id)?;
    let enchantment: Option<Enchantment> =
        sqlx::query_as("SELECT id, name, min_tier, max_tier, image_url FROM enchantments WHERE id = $1")
            .bind(body.enchantment_id)
            .fetch_optional(&state.pool)
            .await?;
    let mut enchantment =
        enchantment.ok_or_else(|| AppError::BadRequest(format!("No enchantment with id {}", body.enchantment_id)))?;
    roll::hydrate_enchantment_attributes(&state.pool, &mut enchantment).await?;

    if let Some(s) = build.enchantments.iter_mut().find(|s| s.tier == tier) {
        s.resolved = Some(enchantment);
        s.requires_manual_pick = false;
    }
    save_build(&state, build.clone());
    Ok(Json(build))
}

#[cfg(test)]
mod tests {
    use std::collections::HashMap;
    use std::sync::{Arc, Mutex};

    use sqlx::PgPool;

    use super::*;
    use crate::models::AghanimTiming;

    fn test_config() -> BuildConfig {
        BuildConfig {
            attack_types: vec![],
            attributes: vec![],
            item_tags: vec![],
            disable_neutral_artifact_randomness: false,
            disable_enchantment_randomness: false,
            disable_all_neutral_rolls: false,
            disabled_item_slots: vec![],
            disable_aghanim_scepter_randomness: false,
            disable_aghanim_shard_randomness: false,
            neutral_tier_reroll_enabled: true,
            aghanim_scepter_timing: AghanimTiming::Anytime,
            aghanim_shard_timing: AghanimTiming::Anytime,
        }
    }

    fn test_state(pool: PgPool) -> AppState {
        AppState { pool, builds: Arc::new(Mutex::new(HashMap::new())), neutral_tier_gate_chance: 1.0 }
    }

    #[sqlx::test]
    async fn post_builds_produces_a_full_build(pool: PgPool) -> sqlx::Result<()> {
        let state = test_state(pool);
        let Json(build) =
            post_builds(State(state), Json(test_config())).await.expect("build generation should succeed");

        assert_eq!(build.item_slots.len(), 6);
        assert_eq!(build.neutral_items.len(), 5);
        assert_eq!(build.enchantments.len(), 5);
        let slot1_name = build.item_slots[0].item.as_ref().unwrap().name.to_lowercase();
        assert!(slot1_name.contains("boots") || slot1_name.contains("treads"));
        Ok(())
    }

    #[sqlx::test]
    async fn reroll_hero_changes_hero_and_keeps_build_id(pool: PgPool) -> sqlx::Result<()> {
        let state = test_state(pool);
        let Json(build) = post_builds(State(state.clone()), Json(test_config())).await.unwrap();
        let original_id = build.id.clone();

        let Json(rerolled) =
            reroll_hero(State(state), Path(original_id.clone())).await.expect("reroll should succeed");

        assert_eq!(rerolled.id, original_id);
        // Enchantments must stay consistent with whichever hero ended up on the build.
        for stage in &rerolled.enchantments {
            if let Some(resolved) = &stage.resolved {
                assert!(resolved.attributes.contains(&rerolled.hero.primary_attribute));
            }
        }
        // Neutral items must have been re-rolled fresh (attempts populated again).
        assert!(rerolled.neutral_items.iter().all(|s| s.attempts.len() == 2));
        Ok(())
    }

    #[sqlx::test]
    async fn reroll_item_slot_only_touches_the_requested_slot(pool: PgPool) -> sqlx::Result<()> {
        let state = test_state(pool);
        let Json(build) = post_builds(State(state.clone()), Json(test_config())).await.unwrap();

        let Json(rerolled) = reroll_item_slot(State(state), Path((build.id.clone(), 3)))
            .await
            .expect("reroll should succeed");

        for original_slot in &build.item_slots {
            if original_slot.slot == 3 {
                continue;
            }
            let same_slot = rerolled.item_slots.iter().find(|s| s.slot == original_slot.slot).unwrap();
            assert_eq!(same_slot.item.as_ref().map(|i| i.id), original_slot.item.as_ref().map(|i| i.id));
        }
        Ok(())
    }

    #[sqlx::test]
    async fn reroll_item_slot_one_stays_boots(pool: PgPool) -> sqlx::Result<()> {
        let state = test_state(pool);
        let Json(build) = post_builds(State(state.clone()), Json(test_config())).await.unwrap();

        let Json(rerolled) =
            reroll_item_slot(State(state), Path((build.id.clone(), 1))).await.expect("reroll should succeed");

        let name = rerolled.item_slots[0].item.as_ref().unwrap().name.to_lowercase();
        assert!(name.contains("boots") || name.contains("treads"));
        Ok(())
    }

    #[sqlx::test]
    async fn unknown_build_id_returns_not_found(pool: PgPool) -> sqlx::Result<()> {
        let state = test_state(pool);
        let result = reroll_hero(State(state), Path("does-not-exist".to_string())).await;
        assert!(matches!(result, Err(AppError::NotFound)));
        Ok(())
    }

    #[sqlx::test]
    async fn patch_item_slot_marks_slot_manual(pool: PgPool) -> sqlx::Result<()> {
        let state = test_state(pool.clone());
        let Json(build) = post_builds(State(state.clone()), Json(test_config())).await.unwrap();

        let (item_id,): (i32,) = sqlx::query_as("SELECT id FROM items WHERE source = 'shop' LIMIT 1")
            .fetch_one(&pool)
            .await?;

        let Json(patched) = patch_item_slot(State(state), Path((build.id.clone(), 2)), Json(ItemIdBody { item_id }))
            .await
            .expect("patch should succeed");

        let slot = patched.item_slots.iter().find(|s| s.slot == 2).unwrap();
        assert!(slot.is_manual);
        assert_eq!(slot.item.as_ref().unwrap().id, item_id);
        Ok(())
    }

    #[sqlx::test]
    async fn patch_item_slot_rejects_unknown_item_id(pool: PgPool) -> sqlx::Result<()> {
        let state = test_state(pool);
        let Json(build) = post_builds(State(state.clone()), Json(test_config())).await.unwrap();

        let result =
            patch_item_slot(State(state), Path((build.id.clone(), 1)), Json(ItemIdBody { item_id: -1 })).await;
        assert!(matches!(result, Err(AppError::BadRequest(_))));
        Ok(())
    }

    #[sqlx::test]
    async fn aghanim_result_reflects_item_slots_after_manual_patch(pool: PgPool) -> sqlx::Result<()> {
        let state = test_state(pool.clone());
        let mut config = test_config();
        config.disable_aghanim_scepter_randomness = false;
        let Json(build) = post_builds(State(state.clone()), Json(config)).await.unwrap();

        let scepter_id: Option<(i32,)> =
            sqlx::query_as("SELECT id FROM items WHERE name = 'Aghanim''s Scepter'").fetch_optional(&pool).await?;
        let Some((scepter_id,)) = scepter_id else {
            // Scepter isn't seeded in this environment -- nothing to verify.
            return Ok(());
        };

        let Json(patched) =
            patch_item_slot(State(state), Path((build.id.clone(), 2)), Json(ItemIdBody { item_id: scepter_id }))
                .await
                .expect("patch should succeed");

        assert!(patched.aghanim_scepter.included);
        assert_eq!(patched.aghanim_scepter.item.unwrap().id, scepter_id);
        Ok(())
    }
}